We are a freight merchant that calculates customs duty payable and invoices that to the customer plus our processing fees. We would like to be able to select a duty tariff code for each line item (let's call that 'a'), input the value of the merchandise being shipped by our customer ('b'), and charge 'a' x 'b' on the customer's invoice. For example, the customer imports $1,000 worth of bananas, the applicable duty rate might be 10%: we want to be able to select the tariff rate for bananas (item?), input $1,000 and have Quickbooks charge the customer $100 (10% x $1,000). Then move onto line item two and choose a different tariff and input a different value and so on. I have tried with service charge rates but this seems to be on all other line item totals rather than line by line, and does not allow me to enter a line item value to multiply out.

We are using QuickBooks Desktop.