You can put this solution on YOUR website! Well if we compare volumes...
A 3x4x5 has 60 cubic units...the 2x2x3 has 12 cubic units....thus five of them should fit, IF they fit in neatly...I suspect this si a trickier problem than simply answering five...one has to look at the practicality of putting 2x2x3 boxes in a 3x4x5 box...