Can round up error occur in Bitcoin?
Like a bunch of 0.00000003 BTC add up to a wrong amount as the price inflate and people split it into a smaller value when spending them?
As far as I understand it, the amount of a bitcoin transaction is in uint64_t satoshis. In a correct implementation, all arithmetic performed on integers is exact, and there's no possibility for the number of satoshis in any transaction to ever exceed the maximum uint64_t.