RAM usage

I dont think you will ever get the exact. This applies not just to RAM, but virtual disk also. There are always very little amount of deviation. I believe this has to do with decimal points. Unless we are able to very accurately define the sizes it will never be the exact.
If we were able to define in bytes, i think we could also see the exact amount. For example, for 32GB we would define 34,359,738,368 bytes. Since bytes are the lowest in the unit it would show the exact allocated memory. Just my opinion.