As per our rounding rules, if the rule is to "round up" per installment, the amount rounded up is subtracted from the principal due on the last installment.
If a loan has a LOT of installments and a very small amount of principal paid on each installment, you could have the scenario where the principal amount due on the last installment is negative (too much has been subtracted from it). If the amount of interest due on that last installment is not sufficient to cover the negative amount of the principal-- you won't be able to make a payment against the loan (since the payment pipeline only accepts positive numbers.)
This will also occur in v1.1 if the rounding rules per payment are much coarser than the currency precision.
If an MFI comes across this issue, they'll notice it when creating the loan account itself.