Apple offering 10% bonus for adding credit to Apple ID
Apple is giving its users an opportunity to earn some bonus credit on the Apple ID to spend on Apple's products and services, by offering 10% extra on top of any additions to an account up to the value of $200 before May 10.

A repeat of a promotion that last took place in March, the offer relates to the ability to add credit to an Apple ID, which can then be used to make payments in the various media and App Stores Apple controls. Running from Tuesday until March 10, customers in the United States with a valid payment card on an account can make a one-time top-up and receive further credit worth 10% of the payment.
According to Apple's terms, the bonus is applied on only one successful top-up during the offer period, and is available for values between $1 and $200. In reality, the amount that can be topped up differs depending on the device used.
On an iOS device, users have to go to the App Store and tap their name, then on Add Funds to Apple ID, then the amount they wish to top up. Via this method, the options are $10, $25, $50, $100, and $200, with each value also displaying the extra credit that users will receive.
On the Mac App Store, the process involves clicking the user's name at the bottom left then selecting View Information, and entering the proper credentials. Under Add Funds to Apple ID, the five values of credit are presented, along with Other, which can be used to select a custom credit amount.

A repeat of a promotion that last took place in March, the offer relates to the ability to add credit to an Apple ID, which can then be used to make payments in the various media and App Stores Apple controls. Running from Tuesday until March 10, customers in the United States with a valid payment card on an account can make a one-time top-up and receive further credit worth 10% of the payment.
According to Apple's terms, the bonus is applied on only one successful top-up during the offer period, and is available for values between $1 and $200. In reality, the amount that can be topped up differs depending on the device used.
On an iOS device, users have to go to the App Store and tap their name, then on Add Funds to Apple ID, then the amount they wish to top up. Via this method, the options are $10, $25, $50, $100, and $200, with each value also displaying the extra credit that users will receive.
On the Mac App Store, the process involves clicking the user's name at the bottom left then selecting View Information, and entering the proper credentials. Under Add Funds to Apple ID, the five values of credit are presented, along with Other, which can be used to select a custom credit amount.
Comments
I remember the days of 25% off, some years ago. I stocked up on iTunes cards big time back then when I came across those kind of deals. Those days are over though I guess. You don't see deals like that anymore.
So, if somebody bought a $50 card, then they would get 30% off of the next $50 card, bringing the total cost for a $100 in iTunes Credits to $85, which is not a very good Black Friday deal, as that's just 15% off, and that's the same discount that all of the current deals are, such as the recent Costco deal.
I'll be keeping an eye out for Black Friday 2019, and I will definitely stock up on some iTunes Credits if I find some good deals. There are a few pricey apps and software that I plan on buying.
You can use it for app/games like you mentioned, but it can also be used on the Mac App Store for any software that's there. It can be used for songs, movies etc, anything that's on the iTunes Store basically I believe.
It can also be used for subscriptions, if you sign up through iTunes, so if somebody wants Netflix for example, then they'd be getting it at a discount. I recently signed up for HBO and I paid using my iTunes credits which I had gotten at a discount.
* Despite that always being stated as 20% off—which used to be common many years ago—by my calculations it’s 19.25% off because you’re only getting the additional 5% back on the amount you are charged, which is $4.25 for $100 GC in which you pay $85.
To note, Netflix no longer allows you to pay for subscription through iTunes, along with some others, Spotify may be one of them. I used to do this because I’d get iTunes gift cards at 15 or 20% off.
10% isn’t bad, but 15 or 20% is better, however, usually 20% off is only for certain amounts, like $100 or maybe $50. (PayPal does 20% from time to time.)
I do know that it worked with HBO just recently.
I get 100% off iTunes by using a VPN and doing a DuckDuckGo search for “song
title 320kbps mp3”