probably none. To handle currency correctly you have to handle rounding to the nearest penny correctly. Computers absolutely SUCK at this, in general. So you

probably none. To handle currency correctly you have to handle rounding to the nearest penny correctly. Computers absolutely SUCK at this, in general. So you need a Decimal library, that can handle decimal numbers. Integers ARE NOT DECIMAL. IBM has had a solution for a long time: http://speleotrove.com/decimal/ http://speleotrove.com/decimal/ Python uses it: https://docs.python.org/3.5/library/decimal.html https://docs.python.org/3.5/library/decimal.html Get a proper decimal library, and then you can devote brain cells to actual problems. The IBM link above includes links to libraries that do it right.