Side anecdote: Many, many years ago, I wrote a lease payment plan calculator for a big bank-linked leasing company when they moved from AS/400 to .Net. I made s

Side anecdote: Many, many years ago, I wrote a lease payment plan calculator for a big bank-linked leasing company when they moved from AS/400 to .Net. I made sure all rounding was policy driven, not only in precision, but also in where roundings would occur during the calculations. 1 cent differences do matter in such environments. Somehow it passed all the extensive regression tests that compared to their mainframe code out of the box with the config based on nothing more than my guesses. AFAIK the code is still in production to this date.