Fix F5.3 check

Created by: cpresser

This fixes a regression from #334 (closed).

---

My testing when making #334 (closed) was not good enough. For some cases the weird +0.00005 math breaks the rounding really bad. I remove that block completely, the rounding is simpler and better. At least my current testing shows that it now works again as intended.

@evanshultz can you please take a look. This breaks travis (false positives). So I would like to address that right away.

See https://github.com/KiCad/kicad-footprints/pull/2438#issuecomment-694928293