Project Contract Billing Invoice Distribution Rounding

For Bill Rate Invoicing contract lines, the system is calculating each expenditure line x bill rate and rounding. Our customer would like for this rounding to not occur, instead they want the rounding to be at a total of hours for the grouped line per the invoice format x rate, then round. On large invoices, this produces differences rejected by their customer portals where they must enter resource, total hours, unit rate, extended amount. This extended amount does not give the same amount as a distribution level rounding.

Is there any way around this? The key item that is off is that the customer has an expectation to bill at total hours x unit rate and then round, whereas the system is performing this calculation at an expenditure level.