System is not calculating Discount based on Item & Excise duty in Receivables

Summary:

System is not calculating Discount based on Item & Excise duty in Receivables which are imported from Order Management (Source: DOO)

1. Currently Tax on order is being calculated based on final price (net price - discount)

2. But customer is expecting the tax to be calculated below based on net price only.

Customer wants tax should get calculated like below.
Customer name: CATRION
Item Price : 6.52
Discount (18.14%): 1.18
Excise Tax (100% of Item Price) : 6.52
selling Price (Item Price+ Excise Tax - Discount) : 11.86
VAT (15%) : 1.78
Total (Selling Price +Vat 15%) : 13.64

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