Does anyone know whether exchanges usually round values or truncate them instead?
Different exchanges support different resolutions for prices and amounts. For instance, BTC China supports 2 decimals for prices and fiat amounts (in CNY) and 4 decimals for BTC amounts.
Now, if I buy, say, 0.625 BTC at price 1621.37, I would get 1013.35625 CNY, but since fiat amounts are allowed to have only 2 decimals, that number will lose the extra digits. But will it become 1013.36 or 1013.35 (that is, rounded or truncated?).
This can be verified empirically for any given exchange, but I was hoping someone already knew the answer, either for specific exchanges or a general rule that most exchanges follow (if that were the case).