Dunlop tube for motor cycle
Over charging

I have purchased one dunlop tube. The MRP of the product was Rs. 248. But when I demanded the bill the shopkeeper has charged 12.5% tax extra. As per my understanding nobody can charge more than MRP as the MRP includes all the taxes. Please suggest can i lodge an FIR against the shopkeeper. If yes under which section of IPC or other criminal law. thanks