As long as the value is greater than zero, the floor function should work for you. For values less than zero, use the ceiling function.
if(p4_z > 0)(floor(p4_z))else(ceiling(p4_z))
@Thais, you can have control over the precision of the dimension measurements that will be displayed in information window or GUI of NX. (Ctrl+2 > Options > Information Window).
If they are generated by NX, I thinks there is no way to modify/control it.