Issue: User would like to specify certain tax rule for a specific customer in India. For example, Display the tax as IGST (18%) instead of SGST (9%) and CGST (9%) currently.

Solution: 

Integrated Goods and Service Tax(inter-state-IGST) refer to the delivery of the goods to a customer located in different state. IGST is computed if the delivery address is in a different state as the warehouse state. As a result, the user request is not possible and system is working as expected. We need to inform and educate user about this.