If I am measuring part properties like volume or mass, I will often use the Part Measure command (Analysis tab->Measure group->Part). That command gives you more control on the precision of the measurement. Wolfgang mentioned that you can set a maximum tolerance, but if you use the Part Properties menu, the best you can do is 1%. With the Part Measure command, you can set the tolerance as tight as you want (for example, 0.01%). Of course, if you have a part with lots of complex faces, the tighter the tolerance, the longer it will take to make the measurement.