If you are a Verizon member and are also a part of the Verizon up reward members program, then you should be able to get a free $5 iTunes/App Store gift card from the rewards service.
To get this, all you have to do is open the My Verizon app on your smartphone, tap the three lines in the top-right corner, go to the Verizon Up tab, scroll all the way to the right and from there, you should see the iTunes/App Store gift card that is available to redeem.
Note that you must have at least one full credit to redeem in order to get this gift card. The gift card can be used for iTunes movie rentals and purchases, TV shows, and music purchases, as well as apps in all versions of the App Store (iOS, Mac, tvOS and watchOS). To sign up for the Verizon Up program, click here.
UPDATE (03/06/2019): This offer has expired.