Depends on what you plan on doing with the hole makes a difference on what size to waterjet.
Clearance hole or tapped and reamed??
We can do holes within +/- .003 or better but takes more time to set up, normally it's easy to just cut under by ~.020" and drill, ream etc.
Pilot hole in in the .060" range is about the smallest we do. The cutting focus tube diameter is .035" in new condition and grows with use.
Our Flow waterjet has a Dynamic cutting head so the taper is eliminated with a little set up time. Or run fixed head and accept a very slight taper that will disappear with your profiling operation, not a big deal.
It also makes a difference on who is doing the waterjetting, lots of shops out there who don't know or give a shit. Make sure you specify notes and tolerances regarding critical features. Also consider edge quality, feed speeds and price go hand in hand.