MRP also includes GST. Which means a customer need not have to pay a price above MRP. If you pay a single rupee over MRP it will go to the pocket of the shop owner not to government. Some shop owners charge GST on MRP. Ideal bill will have reverse calculation. It will have MRP first then it shows the breakup into cost of the product and GST levied. And then net payable amount which should not exceed MRP. In short you need not pay a single rupee over MRP.