Programming a channel narrow will not change how the frequency can be entered, it only causes a different IF filter in the receiver to be switched in or out.
In wideband mode, VHF channels are 15KHz apart and UHF channels are 25KHz apart. To hit every possible combination of 15 and 25 channels you'll need a PLL step size of 5KHz. This is what the TK-X30 series uses and any frequency evenly divisible by 5KHz can be programmed into it (155.360, 155.365, 155.370 etc).
Now the UHF band has for many years has allowed channels in between the normal 25KHz, used to called "splinter" channels. To hit these splinter channels the frequency step needs to be 12.5 KHz. All TK-X30 radios allow 12.5 steps also ( 460.000, 460.0125, 460.025, 460.0375 etc) but that is all they will do.
With narrow banding we have channel spacings of 7.5KHz (half of VHF 15KHz) and 12.5KHz (half of UHF 25KHz). The maximum frequency step that can be used to cover all channel combinations is 2.5KHz. The program software has error checking and won't allow all these new 2.5 channels.
b7spectra is OK with his UHF as this has been in place for a long time, but splitting 15KHz VHF channels is fairly new and was not on the radar when the 30s where designed so the short answer is you will not be able program certain channels unless someone hacks the software to accept the new channels. You could enter the rounded off freqs and warp the radio 2.5KHz to make it work, but then any of the old "normal" freqs would be off.
