Well, duh, first. You program in a channel on 12.5 KHz spacing, no suprise the scanner has to BE in that spacing. Though in fact, the spacing is even smaller than that, in this case, the channels are on 7.5 KHz spacing, and this one just happens to also be a 12.5 KHz channel.
No, not all channels in the 155 range are 5 KHz spacing. They actually have various spacings, used to be mostly 15 or 20 KHz, now being converted to smaller spacings. Depending on the original spacing, they may be at 12.5, 7.5, or 6.25 KHz spacing now!
From the current FCC regs for Part 90 (Public Safety Pool)
155.220 ............ ......do .............. 10 ............. PS
155.2275 .......... ......do .............. 10, 27 ...... PS
155.235 ............ ......do .............. 10 ............. PS
155.2425 .......... ......do .............. 10, 27 ...... PS
155.250 ............ ......do .............. .................. PP
155.2575 .......... ......do .............. 27 ............. PP
155.265 ............ ......do .............. 10 ............. PS
155.2725 .......... ......do .............. 10, 27 ...... PS
155.280 ............ ......do .............. 10 ............. PS
155.2875 .......... ......do .............. 10, 27 ...... PS
155.295 ............ ......do .............. 10 ............. PS
155.3025 .......... ......do .............. 10, 27 ...... PS
155.310 ............ ......do .............. .................. PP
155.3175 .......... ......do .............. 27 ............. PP
155.325 ............ ......do .............. 10, 39 ...... PM
155.3325 .......... ......do .............. 27, 10, 39 PM
155.340 ............ ......do .............. 39, 40 ...... PM
155.3475 .......... ......do .............. 27, 39, 40 PM
155.355 ............ ......do .............. 10, 39 ...... PM
155.3625 .......... ......do .............. 27, 10, 39 PM
155.370 ............ ......do .............. .................. PP
155.3775 .......... ......do .............. 27 ............. PP
155.385 ............ ......do .............. 10, 39 ...... PM
155.3925 .......... ......do .............. 27, 10, 39 PM
155.400 ............ ......do .............. 10, 39 ...... PM
155.4075 .......... ......do .............. 27, 10, 39 PM
155.415 ............ ......do .............. .................. PP
155.4225 .......... ......do .............. 27 ............. PP
155.430 ............ ......do .............. .................. PP
155.4375 .......... ......do .............. 27 ............. PP
155.445 ............ ......do .............. 16 ............. PP
155.4525 .......... ......do .............. 16, 27 ...... PP
155.460 ............ ......do .............. 16 ............. PP
155.4675 .......... ......do .............. 16, 27 ...... PP
155.475 ............ ......do .............. 41 ............. PP
155.4825 .......... ......do .............. 27, 41 ...... PP
155.490 ............ ......do .............. .................. PP
155.4975 .......... ......do .............. 27 ............. PP
155.505 ............ ......do .............. 16 ............. PP
155.5125 .......... ......do .............. 16, 27 ...... PP
155.520 ............ ......do .............. .................. PP
155.5275 .......... ......do .............. 27 ............. PP
155.535 ............ ......do .............. .................. PP
155.5425 .......... ......do .............. 27 ............. PP
155.550 ............ ......do .............. .................. PP
155.5575 .......... ......do .............. 27 ............. PP
155.565 ............ ......do .............. .................. PP
155.5725 .......... ......do .............. 27 ............. PP
155.580 ............ ......do .............. .................. PP
155.5875 .......... ......do .............. 27 ............. PP
155.595 ............ ......do .............. .................. PP
155.6025 .......... ......do .............. 27 ............. PP
155.610 ............ ......do .............. .................. PP
155.6175 .......... ......do .............. 27 ............. PP
155.625 ............ ......do .............. .................. PP
155.6325 .......... ......do .............. 27 ............. PP
155.640 ............ ......do .............. .................. PP
155.6475 .......... ......do .............. 27 ............. PP
155.655 ............ ......do .............. .................. PP
155.6625 .......... ......do .............. 27 ............. PP
155.670 ............ ......do .............. .................. PP
155.6775 .......... ......do .............. 27 ............. PP
155.685 ............ ......do .............. .................. PP
155.6925 .......... ......do .............. 27 ............. PP
155.700 ............ ......do .............. .................. PP
155.7075 .......... ......do .............. 27 ............. PP
155.715 ............ ......do .............. .................. PX
155.7225 .......... ......do .............. 27 ............. PX
155.730 ............ ......do .............. .................. PP
155.7375 .......... ......do .............. 27 ............. PP
