Gmodrp money problem

Ok here is the problem,in all versions from 1.1 to 1.5 beta and beta 2,money is very bugged…lets say it this way,i am a store owner,my friend come o buy a mellon,i sell hima mellon,he drops 20 ,but he gets 45 ,and when i pick up the 20 i get -50 ,like the pc isnt calculating the money good…,or i drop 12 $ and i lose 20,when i pick it up i earn 54…OMG!!!plz help me,and dont suggest me the darp rp,it sucks!!i really need help with thios problem!!