If you buy X you pay tax. If you donate to provider of X and get X in return as a gift you don't pay tax. For example donating money to keep your local church

If you buy X you pay tax. If you donate to provider of X and get X in return as a gift you don't pay tax. For example donating money to keep your local church running is paying for a service without paying taxes for it. Another thing you can do is donate earmarked money that they will use to buy your products. For example Google donating chromebooks to schools. That is marketing dollars.