I will add this to the issue at my previous employer: it was an inherited system (was supported by an outside company and brought internal) that was written entirely in spagetti COBOL. The way discounts were applied forced how we had to do it, and yes, how rounding was implemented was a part of it, as was how we had to report the discounts.
It was a mess, and I helped support it for 11 years (well past when it should have been rewritten) and it is still used today. I would have loved to been a fly on the wall when the s*** hit the wall last year on May 18th. Fours earlier I had warned them about an issue in the system that would fail after May 17th, 2007; and had even put together a remediation plan to fix it but was told "We'll be off the system before then." Ha. Took the developers a week or so to fix the problem and the data.
You take what your dealt, and work with it. If you can improve it, great, if not, oh well.
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