So i'm trying to renew my domain but I want to use some coupon codes since I can't currently afford the $25 that it costs. I have found multiple coupon codes that say they are valid when I redeem them but they don't reduce the cost. Take a look at a photo here: http://prntscr.com/h6e5ng
Coupon codes are no longer available for renewals and have not been for some time. If you have over 21 domains, you can purchase the Discount Domains Club for $120 per year and the savings will outweigh the cost, otherwise renewals are at regular price.
If you have fewer than 21 domains and you want to do an extended renewal (such as 5 or more years) you can call in and you might be able to get a discount for a long term renewal but not for a year or two.