Apple App Store is offering a 10% bonus when you add funds to your Apple ID (max bonus of $20)
Step 1 On your iPhone, go to the App Store
Step 2 Tap on Apple ID profile on the top right
Step 3 Tap "Add funds to Apple ID"
Step 4 Add the amount you'd like. You will get 10% in bonus up to $20 * Add $10, you will get $1 * Add $25, you will get $2.50 * Add $50, you will get $5 * Add $100, you will get $10 * Add $200, you will get $20
Step 5 After you authorize the payment, the funds credit to your Apple ID
Apple Funds can be used on the following * App Store * iTunes Store * Apple Books * iCloud Storage