I would send that to your VAR as a bug. It may be tied in with another bug--see the thread "Re: Spin block not accurate in 2012" in the "More Like This" block to the right. I believe that one is supposed to be fixed with SP1, so perhaps yours will be as well.
If SW decides it is not a bug and doesn't fix it, then all I can think of are various workarounds, like setting up your templates with 4 or 5 places, then using a 3 place favorite to switch the number of places just before you release them to the shop.
Looks like there is a bug. Here is the SPR# from SolidWorks.
SR# (Service Request): 1-2337943831
Description: Spin box increment length value is rounded to units precision when changed in modify dimension dialog
Version: none none