You are correct, you cannot just set your step for 15 kHz (or 7.5 kHz now), and search the entire band. This list, writen before the FCC has been issuing licences 7.5 kHz apart, should show where things change.
freq, old desig, new desig
150.775,PM,PW
150.79,PM,PW
150.805,PM,PW
----------------------------------------------------------------
150.815,LA,IG
150.83,LA,IG
150.845,LA,IG
150.86,LA,IG
150.875,LA,IG
150.89,LA,IG
150.905,LA,IG
150.92,LA,IG
150.935,LA,IG
150.95,LA,IG
150.965,LA,IG
150.98,IP,IG
150.995,PH,PW
151.01,PH,PW
151.025,PH,PW
151.04,PH,PW
151.055,PH,PW
151.07,PH,PW
151.085,PH,PW
151.1,PH,PW
151.115,PH,PW
151.13,PH,PW
151.145,PO,PW
151.16,PO,PW
151.175,PO,PW
151.19,PO,PW
151.205,PO,PW
151.22,PO,PW
151.235,PO,PW
151.25,PO,PW
151.265,PO,PW
151.28,PO,PW
151.295,PO,PW
151.31,PO,PW
151.325,PO,PW
151.34,PO,PW
151.355,PO,PW
151.37,PO,PW
151.385,PO,PW
151.4,PO,PW
151.415,PO,PW
151.43,PO,PW
151.445,PO,PW
151.46,PO,PW
151.475,PO,PW
151.49,PO,PW
151.505,IS,IG
151.52,IS,IG
151.535,IS,IG
151.55,IS,IG
151.565,IS,IG
151.58,IS,IG
151.595,IS,IG
151.61,(gap),IG
151.625,IB Red Dot,IG
151.64,(gap),IG
151.655,IB SP10,IG
151.67,(gap),IG
151.685,IB SP10,IG
151.7,(gap),IG
151.715,IB SP10,IG
151.73,(gap),IG
151.745,IB,IG
151.76,(gap),IG
151.775,IB SP10,IG
151.79,(gap),IG
151.805,IB SP10,IG
151.82,(gap),IG
151.835,IB SP10,IG
151.85,(gap),IG
151.865,IB,IG
151.88,(gap),IG
151.895,IB SP10,IG
151.91,(gap),IG
151.925,IB SP10,IG
151.94,(gap),IG
151.955,IB SP10,IG
151.97,(gap),IG
151.985,IT,IG
152,(gap),
152.0075,Page,PW
152.015,(gap),
152.03,CD,IG
152.045,(gap),IG
152.06,CD,IG
152.075,(gap),IG
152.09,CD,IG
152.105,(gap),IG
152.12,CD,IG
152.135,(gap),IG
152.15,CD,IG
152.175,(gap),IG
152.18,CD,IG
152.195,(gap),IG
152.21,CD,IG
152.225,(gap),IG
152.24,CD,IG
152.255,(gap),IG
152.27,LX,IG
152.285,LX,IG
152.3,LX,IG
152.315,LX,IG
152.33,LX,IG
152.345,LX,IG
152.36,LX,IG
152.375,LX,IG
152.39,LX,IG
152.405,LX,IG
152.42,LX,IG
152.435,LX,IG
152.45,LX,IG
152.465,LX,IG
152.48,IB,IG
152.495,(gap),IG
152.51,CD,IG
152.525,(gap),IG
152.54,CD,IG
152.555,(gap),IG
152.57,CD,IG
152.585,(gap),IG
152.6,CD,IG
152.615,(gap),IG
152.63,CD,IG
152.645,(gap),IG
152.66,CD,IG
152.675,(gap),IG
152.69,CD,IG
152.705,(gap),IG
152.72,CD,IG
152.735,(gap),IG
152.75,CD,IG
152.765,(gap),IG
152.78,CD,IG
152.795,(gap),IG
152.81,CD,IG
152.835,(gap),IG
152.84,CD,IG
152.855,(gap),IG
152.87,IM IS,IG
152.885,IS,IG
152.9,IM IS,IG
152.915,IS,IG
152.93,IM IS,IG
152.945,IS,IG
152.96,IM IS,IG
152.975,IS,IG
152.99,IM IS,IG
153.005,IS,IG
153.02,IM IS,IG
153.035,IP IS,IG
153.05,IP IF IX,IG
153.065,IP IF IX,IG
153.08,IP IF IX,IG
153.095,IP IF IX,IG
153.11,IP IF IX,IG
153.125,IP IF IX,IG
153.14,IP IF IX,IG
153.155,IP IF IX,IG
153.17,IP IF IX,IG
153.185,IP IF IX,IG
153.2,IP IF IX,IG
153.215,IP IF IX,IG
153.23,IP IF IX,IG
153.245,IP IF IX,IG
153.26,IP IF IX,IG
153.275,IP IF IX,IG
153.29,IP IF IX,IG
153.305,IP IF IX,IG
153.32,IP IF IX,IG
153.335,IP IF IX,IG
153.35,IP IF IX,IG
153.365,IP IF IX,IG
153.38,IP IF IX,IG
153.395,IP IF IX,IG
153.41,IW,IG
153.425,IW,IG
153.44,IW,IG
153.455,IW,IG
153.47,IW,IG
153.485,IW,IG
153.5,IW,IG
153.515,IW,IG
153.53,IW,IG
153.545,IW,IG
153.56,IW,IG
153.575,IW,IG
153.59,IW,IG
153.605,IW,IG
153.62,IW,IG
153.635,IW,IG
153.65,IW,IG
153.665,IW,IG
153.68,IW,IG
153.695,IW,IG
153.71,IW,IG
153.725,IW,IG
153.74,PX,PW
153.755,PX,PW
153.77,PF,PW
153.785,PX,PW
153.8,PX,PW
153.815,PX,PW
153.8225,,PW
153.83,PF,PW
153.845,PX,PW
153.86,PX,PW
153.875,PX,PW
153.89,PF,PW
153.905,PX,PW
153.92,PX,PW
153.935,PX,PW
153.95,PF,PW
153.965,PX,PW
153.98,PX,PW
153.995,PX,PW
154.01,PF,PW
154.025,PX,PW
154.04,PX,PW
154.055,PL,PW
154.07,PF,PW
154.085,PX,PW
154.1,PX,PW
154.115,PX,PW
154.13,PF,PW
154.145,PF,PW
154.16,PF,PW
154.175,PF,PW
154.19,PF,PW
154.205,PF,PW
154.22,PF,PW
154.235,PF,PW
154.25,PF,PW
154.265,PF,PW
154.28,PF,PW
154.295,PF,PW
154.31,PF,PW
154.325,PF,PW
154.34,PF,PW
154.355,PF,PW
154.37,PF,PW
154.385,PF,PW
154.4,PF,PW
154.415,PF,PW
154.43,PF,PW
154.445,PF,PW
----------------------------------------------------------------
154.45625,,IG
154.46375,,IG
154.47125,,IG
154.47875,,IG
154.49,IS SP10,IG
154.515,IB SP10,IG
154.54,IB SP10,IG
154.57,IB Blue Dot,IG
154.585,IP,IG
154.6,IB Green Dot,IG
154.625,IB,IG
----------------------------------------------------------------
154.65,PP,PW
154.665,PP,PW
154.68,PP,PW
154.695,PP,PW
154.71,PP,PW
154.725,PP,PW
154.74,PP,PW
154.755,PP,PW
154.77,PP,PW
154.785,PP,PW
154.8,PP,PW
154.815,PP,PW
154.83,PP,PW
154.845,PP,PW
154.86,PP,PW
154.875,PP,PW
154.89,PP,PW
154.905,PP,PW
154.92,PP,PW
154.935,PP,PW
154.95,PP,PW
154.965,PX,PW
154.98,PX,PW
154.995,PX,PW
155.01,PP,PW
155.025,PX,PW
155.04,PX,PW
155.055,PX,PW
155.07,PP,PW
155.085,PX,PW
155.1,PX,PW
155.115,PX,PW
155.13,PP,PW
155.145,PX,PW
155.16,PS,PW
155.175,,
155.19,PP,PW
155.205,PS,PW
155.22,PS,PW
155.235,PS,PW
155.25,PP,PW
155.265,PS,PW
155.28,PS,PW
155.295,PS,PW
155.31,PP,PW
155.325,PM,PW
155.34,PM,PW
155.355,PM,PW
155.37,PP,PW
155.385,PM,PW
155.4,PM,PW
155.415,PP,PW
155.43,PP,PW
155.445,PP,PW
155.46,PP,PW
155.475,PP,PW
155.49,PP,PW
155.505,PP,PW
155.52,PP,PW
155.535,PP,PW
155.55,PP,PW
155.565,PP,PW
155.58,PP,PW
155.595,PP,PW
155.61,PP,PW
155.625,PP,PW
155.64,PP,PW
155.655,PP,PW
155.67,PP,PW
155.685,PP,PW
155.7,PP,PW
155.715,PX,PW
155.73,PP,PW
155.745,PX,PW
155.76,PX,PW
155.775,PX,PW
155.79,PP,PW
155.805,PX,PW
155.82,PX,PW
155.835,PX,PW
155.85,PP,PW
155.865,PX,PW
155.88,PX,PW
155.895,PX,PW
155.91,PP,PW
155.925,PX,PW
155.94,PX,PW
155.955,PX,PW
155.97,PP,PW
155.985,PX,PW
156,PX,PW
156.015,PX,PW
156.03,PP,PW
156.045,PH,PW
156.06,PH,PW
156.075,PH,PW
156.09,PP,PW
156.105,PH,PW
156.12,PH,PW
156.135,PH,PW
156.15,PP,PW
156.165,PH,PW
156.18,PH,PW
156.195,PH,PW
156.21,PP,PW
156.225,PH,PW
156.24,PH,PW
----------------------------------------------------------------
157.025,(gap),PW
157.45,PS,PW
----------------------------------------------------------------
157.47,LA,IG
157.485,LA,IG
157.5,LA,IG
157.515,LA,IG
157.53,LX,IG
157.545,LX,IG
157.56,LX,IG
157.575,LX,IG
157.59,LX,IG
157.605,LX,IG
157.62,LX,IG
157.635,LX,IG
157.65,LX,IG
157.665,LX,IG
157.68,LX,IG
157.695,LX,IG
157.71,LX,IG
157.725,LX,IG
157.74,IB,IG
157.755,(gap),IG
157.77,CD,IG
157.785,(gap),IG
157.8,CD,IG
157.815,(gap),IG
157.83,CD,IG
157.845,(gap),IG
157.86,CD,IG
157.875,(gap),IG
157.89,CD,IG
157.905,(gap),IG
157.92,CD,IG
157.935,(gap),IG
157.95,CD,IG
157.965,(gap),IG
157.98,CD,IG
157.995,(gap),IG
158.01,CD,IG
158.025,(gap),IG
158.04,CD,IG
158.055,(gap),IG
158.07,CD,IG
158.085,(gap),IG
158.1,CD,IG
158.115,(gap),IG
158.13,IW,IG
158.145,IW,IG
158.16,IW,IG
158.175,IW,IG
158.19,IW,IG
158.205,IW,IG
158.22,IW,IG
158.235,IW,IG
158.25,IW,IG
158.265,IW,IG
158.28,IP IF IX,IG
158.295,IP IF IX,IG
158.31,IP IF IX,IG
158.325,IP IF IX,IG
158.34,IT,IG
158.355,IP IF,IG
158.37,IP IF,IG
158.385,IS,IG
158.4,IS SP10,IG
158.415,IP IF IX,IG
158.43,IP IF IX,IG
158.445,IP,IG
158.46,IB,IG
158.475,(gap),IG
158.49,CD,IG
158.505,(gap),IG
158.52,CD,IG
158.535,(gap),IG
158.55,CD,IG
158.565,(gap),IG
158.58,CD,IG
158.595,(gap),IG
158.61,CD,IG
158.635,(gap),IG
158.64,CD,IG
158.655,(gap),IG
158.67,CD,IG
158.685,(gap),IG
158.7,CD,IG
158.715,(gap),IG
158.73,PP,PW
158.745,PX,PW
158.76,PX,PW
158.775,PX,PW
158.79,PP,PW
158.805,PX,PW
158.82,PX,PW
158.835,PX,PW
158.85,PP,PW
158.865,PX,PW
158.88,PX,PW
158.895,PX,PW
158.91,,PW
158.925,PX,PW
158.94,PX,PW
158.955,PX,PW
158.97,PP,PW
158.9775,,PW
158.985,PH,PW
159,PH,PW
159.015,PH,PW
159.03,PP,PW
159.045,PH,PW
159.06,PH,PW
159.075,PH,PW
159.09,PP,PW
159.105,PH,PW
159.12,PH,PW
159.135,PH,PW
159.15,PP,PW
159.165,PH,PW
159.18,PH,PW
159.195,PH,PW
159.21,PP,PW
159.225,PO,PW
159.24,PO,PW
159.255,PO,PW
159.27,PO,PW
159.285,PO,PW
159.3,PO,PW
159.315,PO,PW
159.33,PO,PW
159.345,PO,PW
159.36,PO,PW
159.375,PO,PW
159.39,PO,PW
159.405,PO,PW
159.42,PO,PW
159.435,PO,PW
159.45,PO,PW
159.465,PO,PW
159.48,IP,IG
159.495,LM,IG
159.51,LM,IG
159.525,LM,IG
159.54,LM,IG
159.555,LM,IG
159.57,LM,IG
159.585,LM,IG
159.6,LM,IG
159.615,LM,IG
159.63,LM,IG
159.645,LM,IG
159.66,LM,IG
159.675,LM,IG
159.69,LM,IG
159.705,LM,IG
159.72,LM,IG
159.735,LM,IG
159.75,LM,IG
159.765,LM,IG
159.78,LM,IG
159.795,LM,IG
159.81,LM,IG
159.825,LM,IG
159.84,LM,IG
159.855,LM,IG
159.87,LM,IG
159.885,LM,IG
159.9,LM,IG
159.915,LM,IG
159.93,LM,IG
159.945,LM,IG
159.96,LM,IG
159.975,LM,IG
159.99,LM,IG
160.005,LM,IG
160.02,LM,IG
160.035,LM,IG
160.05,LM,IG
160.065,LM,IG
160.08,LM,IG
160.095,LM,IG
160.11,LM,IG
160.125,LM,IG
160.14,LM,IG
160.155,LM,IG
160.17,LM,IG
160.185,LM,IG
160.2,LM,IG
----------------------------------------------------------------
162,,IG
163.25,PS,PW
166.25,PF,PW
169.445,,IG
169.505,,IG
170.15,,RP
170.245,,IG
170.305,,IG
171.105,,IG
171.905,,IG
173.075,,PW
173.20375,,IG
173.21,,PW
173.225,,IG
173.235,,IG
173.2375,,IG
173.25,,IG
173.25,,IG
173.2625,,IG
173.275,,IG
173.2875,,PW IG
173.3,,IG
173.3125,,PW
173.325,,IG
173.35,,IG
173.3625,,IG
173.3625,,IG
173.375,,IG
173.39,,PW IG
173.39625,,IG
174,,LP