How Can The Shop-Keeper Still Make Profit?

Find the answer to this tough Whatsapp Riddle. There is a shop that reads: Buy 1 for $10.00 10 for $20.00 100 for $30.00 I needed 740 and still only paid $30.00. How can the shop-keeper still make profit? So were you able to solve the riddle? Leave your answers in the comment section below.