Bill payments in foreign currencies

I am paying bills in foreign currencies.
In NetSuite I have to enter the amount paid in the foreign currency and the exchange rate.
Unfortunately I never have the exact exchange rate; I know what I am paying in a foreign currency and what goes out from my bank account in my base currency.
Hence I am generating small "Exchange Rate Variances", which are in reality rounding errors.

Is there a way of paying bills in foreign currency by entering the money paid in the foreign currency and what actually went out of my bank account in my currency?
(These two informations would be sufficient for NetSuite to calculate the actual "Exchange Rate Variances".)