There is another problem with rounding when dealing with currency. When you create a journal entry in a double-entry bookkeeping system, calculating the individual entries by rounding often leads you a penny or two off for the total. So you have to add that discrepancy to an arbitrary entry to get the journal to balance. And then, if someone watching is really crazy, you've got to give the discrepancy to a different account the next month, etc. Just saying...