In several of the GS aircraft I can't tun in the ILS freq 111.10. The freq advance by .05(from 111.01 to 111.06 to 111.11???(Beech Baron, C208 a/c) King Air works fine!

Which sim?

In FSX it works fine for me.

In FSX. I got some help, and have a "work around", but don't know if it will "stick". By sellecting the ILS frq in the GPS screen it tunes OK and works fine. I can then set the 111.10 and change in the .05 KHZ to get correct freqs.

Try loading the default flight/motor kite first and load your chosen aircraft over the top.
Certain FS9---->FSX ports can also have this issue or cause the heading bug selector to increment/decrement in 5 degree "jumps".