There are special deals waiting for you in the "Offers for You" section of a retailer's store, depending on the retailer. You will be able to enjoy a nice discount when you buy a voucher in bulk. A typical in-app deal would be "Buy 10 Coffees for the Price of 8".
You pay for your in-app purchase upfront and will receive your multi-use voucher immediately after. Get more than you paid for!