Floats are not how you do money math, if you run into anyone trying to do money math and they say they use floats, there is a 99.999999% chance they are wrong.
> Maybe you value arithmetic correctness over simplicity of procedures
Lots of places(not typically the USA) has this codified in law. For example, do a web search for: EU money rounding rules. You will find several different rounding and precision rules, depending on the context of what you are doing with the money, all from places like the Central Bank and the EU Commission.
It's mostly US developers that are clueless here, because US laws are fuzzy at best, and the general rule is, you do whatever your bank/regulatory authority does, and if they don't happen to know (and I've met several that don't), then you have to figure it out yourself.
In the USA, we use decimal.ROUND_HALF_UP, because we have seen in practice this is what our USA based banks & govt tend to do in the wild.
It should be noted IEEE 754 rounding recommends using decimal.ROUND_HALF_EVEN. https://en.wikipedia.org/wiki/IEEE_754#Rounding_rules
In other places, we do whatever their laws require, or treat them like the USA and do whatever our local bank/govt authority tends to do in practice.
> Maybe you value arithmetic correctness over simplicity of procedures
Lots of places(not typically the USA) has this codified in law. For example, do a web search for: EU money rounding rules. You will find several different rounding and precision rules, depending on the context of what you are doing with the money, all from places like the Central Bank and the EU Commission.
It's mostly US developers that are clueless here, because US laws are fuzzy at best, and the general rule is, you do whatever your bank/regulatory authority does, and if they don't happen to know (and I've met several that don't), then you have to figure it out yourself.
In the USA, we use decimal.ROUND_HALF_UP, because we have seen in practice this is what our USA based banks & govt tend to do in the wild. It should be noted IEEE 754 rounding recommends using decimal.ROUND_HALF_EVEN. https://en.wikipedia.org/wiki/IEEE_754#Rounding_rules
In other places, we do whatever their laws require, or treat them like the USA and do whatever our local bank/govt authority tends to do in practice.