If you want to change an existing dimension, select it, right-click, choose Properties, Units/Tolerance, then change the Precision and Round Off values appropriately.
If you want to change the default for new dimensions, select the required dimension tool, then right-click, choose Properties and then continue as above. New dimension created with that tool will have the required properties.
TC21.2 x64 Plat, Bld59
TC16.2 Plat, Bld54.0