Here's how you can get Amazon to donate to the NRA on your behalf. All you have to do is go through their Amazon Smile program and select the NRA Foundation.
Copied from this NRA BLOG POST
Support The NRA Foundation and our Second Amendment rights every time you shop on Amazon
Fairfax, Virginia - The NRA Foundation, America's leading charitable organization in support of the shooting sports, is now a part of AmazonSmile.
What's AmazonSmile? It's a philanthropy program that contributes a portion of your Amazon.com purchase to a charity of your choice. And there's no additional cost passed on to you. Amazon takes the donation out of their end and will continue to offer its vast selection of products at the same low prices you've come to expect.
Nearly one million charities are featured on AmazonSmile, but with the addition of The NRA Foundation, there's no better organization to support firearm-related public interest activities that promote fun and safety and encourage the next generation of firearms enthusiasts.
If you already have an Amazon account you can add AmazonSmile right on top. No new registration required! To add The NRA Foundation as your charity, sign in at https://smile.amazon.com/
Once logged in:
Click on Your Account to the right of the search bar.
Under Settings category: Select Change Your Charity
Search for “The NRA Foundation, Inc.”
Click Select next to The NRA Foundation, Inc.
Then continue shopping as usual.
Contributions are submitted back to the Foundation through quarterly payments to the Foundation general contribution fund. Any donations to the Foundation prior to August 21, 2014 will be consolidated into our next quarterly payment from AmazonSmile.