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We’ve processed millions of dollars and we have never encountered any sort of rounding issues. Our numbers always match to the penny. Yes, banks do all sorts of
by gizmo 3y ago
We’ve processed millions of dollars and we have never encountered any sort of rounding issues. Our numbers always match to the penny. Yes, banks do all sorts of rounding internally, but this doesn’t affect us. We get detailed transaction statements from the bank (correct to the penny) that contain amounts, currencies, fees, interest, settlement dates and everything else. We take that data and match it to our invoices.
The bank’s numbers are authoritative. We don’t know what spot forex rate the bank will use for any given transaction. We don’t know what fees we get charged. There is no such thing as a disagreement with the bank about how much money we have. Our bank accounts were empty a decade ago. Sum all transactions between then and now and you end up with our current balance, to the penny.
There are some edge cases, where for instance your quarterly numbers are reported individually (and therefore rounded) but the annual report uses unrounded quarterly numbers but this is all pretty straightforward.
Unnecessary complexity would lead to rounding footguns, but money in my world is discrete and fixed precision (just like physical).
- zie 3y agoThen you won the rounding lottery. It's great that you and the bank each round the same way. Also I'm jealous you only have 1 bank to deal with. We have many banks we do business with, one of them rounds differently than the rest. It was fun to figure out how they rounded :) Even more fun altering our software to round differently for transactions involving that bank.
- gizmo 3y agoI can imagine it's a real headache. Maybe I'm surprised because our bank just doesn't do any rounding. It's all fixed point math. Except for fees, but we don't try to reverse-engineer that black box algorithm :)
- zie 3y ago> our bank just doesn't do any rounding. It's all fixed point math. I promise they and you round. As I linked above via Wikipedia, there are many rounding strategies. From what you describe, I'd guess they are Rounding toward zero, i.e. just truncating all digits past 2 decimal places, which is a very reasonable rounding strategy for banks.
- meekaaku 3y agoMaybe they are doing Banker's rounding?
- zie 3y agoFirst you need to be more specific than that, as many people have different meanings to that phrase. Please read the links I sent up-thread, so you can learn that rounding is much more complicated than you appear to think. If you mean: "Rounds to the nearest value; if the number falls midway it is rounded to the nearest value with an even (zero) least significant bit." Then yes I agree it's commonly used by banks in the USA. I promise though that not every bank in the USA uses it, or they might have subtle differences. Also banks outside the USA might have their own common rounding methods. If you are in the EU, they regulate how to round their EU currency(again, see the link I gave upthread, where I link to the EU standard). Rounding is complicated.