Big Business 8.7 adds Currency support to the Invoice Line Item Import.
This Solution describes using this entry. (6320)
To use Currencies on the Invoice Line Item Import, map amounts to FX Other Charges, FX - Price, or FX - Paid. These entries overwrite the amount in native currencies using the current Exchange Rate for the Currency assigned to the Customer.
If a Currency is assigned to the Customer and FX Price is not mapped, the current native currency Price for the Item is applied at the current Exchange Rate for the Currency.