I'm using Win 7 and SU Pro 2015. In the version I have you can set the display precision to display to a given no of decimal points, I normally operate in mm and no decimals for house layout and woodwork tasks, as that's around the normal accuracy I could achieve in my dreams with a steel rule, though I might go one decimal place for something in metal if I going to turn it or mill it and will be using calipers/verniers for measurement.
This does not mean that components that should match may have 1mm overall variance between them, because if the are supposed to match, they are cut/machined as a set using the same setup, stop block positions etc to maintain consistency and matching. There might be +/- 0.5mm deviation from specified final dimension, but all matched components will match properly.
For mine I can set the number of decimal places from the Window, Model Information, Units window, but I understand that you are using a Mac computer so things will invariably be different. I am a passable user rather than an expert, but I am not aware of SU being able to run scripts etc llike the major drafting programs.
I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.