When making a purchase in store, Apple employees will ask customers if they would like to pay via Apple Pay. If a customer declines and does not have Apple Pay set up, employees will guide customers through the setup process to make the purchase and will offer a bonus $5 or £5 iTunes gift card for using Apple Pay as their payment method.
The gift cards are available to customers for any Apple Store purchase. If you return the product you bought, you'll still be able to keep the gift card for having set up Apple Pay.
Notably, Apple Pay just launched in France, making the company's mobile payment service available in a total of eight countries including the USA, Canada, UK, China, Australia, Switzerland, Singapore, and France.