Dual TAX on the Single Product

How to Apply Dual Tax on a Single Product.
Unit Cost - 15688
VAT @ 5% - 784.40
Service Tax @ 12.36% - 2035.99 (on the total of Unit Cost + VAT)
Grand Total - 18508.39

You will need to create new custom tax code under Tax Codes module which is under Settings tab.

Your new tax code will need to have two tax components, VAT 5% and Service Tax 12.36%.