A method and system for stacking containers each container of a type having a front face having a truncated trapezoidal shape, a rear face having a truncated trapezoidal shape, a top base, a bottom base, a first vertical side adjacent to the top base, a second vertical side adjacent to the top base, a first sloped side between the first vertical side and the bottom base, a second sloped side between the second vertical side and the bottom base. A discharge valve projects from the bottom base where the first vertical side defines a platform for supporting an RFID tag. The containers are configured to be stackable in a manner to provide simultaneous reading of the multiple RFID tags on the platforms.