Oracle R12, Entered Foreign currency invoice but paid in Functional ledger currency

Situation where we deduct manually a tax withholding from foreign vendors ie US$ invoice and US vendor - but we remit that withholding to Gov't in CAD$ as this is the requirement in Canada. Issue is around Entered currency amounts for the vendor invoice withholding, never goes away.

Is there a way to enter the Gov't invoice in USD$ same as what was deducted from vendor, but alway pay the Gov't vendor in CAD$. I see on Supplier setups there are two distinct fields for key payment setups screen; Invoice Currency and Payment Currency. Presently the Gov't vendor is setup with both as the same as the functional ledger currency of CAD.