Do they do USD interest calculations in something smaller than 1&#x2F;10000 (decimill I think)?<p>The issue with BCD would be data store support and CPU support right? Do CPUs support doing math directly with BCD values and does your DB support doing math directly with BCD values?<p>In any case, using floating point for any currency calculations is a huge no-no, even though a lot of things do it anyway.<p>I work with Magento daily and all their currency math uses PHP floats and the rounding errors drive me bonkers.