iExpense - Calculating Tax Code based on Exp Type and Location

Hello

I have a requirement in iExpense to default the tax code based on the expense type and the location.

The tax code should be calculated using the expense type and the place of purchase (Location field), as a result, employees do not need to enter the sales tax line independently.

I know that its not possible out of the box to do this. So, I would need to customize this.

I can store the location and tax codes in a table and can use it to automatically calculate taxes.

Can anyone help to with the following:

1. Which package/procedure needs to be modified to to this