If theres a fixed weighting between what the user provides, and what is minted for them, there should be code that tracks partial token amounts, so that later payments are compensated for their prior partial amounts.
There is 1 instance of this issue:
https://github.com/jbx-protocol/juice-contracts-v2-code4rena/blob/828bf2f3e719873daa08081cfa0d0a6deaa5ace5/contracts/JBSingleTokenPaymentTerminalStore.sol#L385-L390
