How to define a Withholding Tax based on the Invoice Total Amount

Summary:

To comply with an Argentinean withholding tax requirement in Accounts Payable, we have to setup a Withholding Tax to be calculated at Payment time, where the Taxable Basis Amount is not equal to the Invoice Line Amount, but to the Invoice Line Amount plus all the Transaction Taxes calculated at invoice time, meaning Invoice Total Amount. How can I do that in Fusion Tax? How can I make the system to use the Invoice Total Amount of the invoice (including all calculated transaction taxes), instead of the invoice line amount?

Content (please ensure you mask any confidential information):

An AP invoice has, for example, two transaction taxes calculated at invoice validation time: