Oh, for Pete's sake! If you don't want to donate, don't donate, but at least get the facts, please. There's plenty of stuff in the world to get angry about right now that's real. In reality:

• The store has to book your donation as "unearned revenue," that is, money it collected, but is not theirs. Charitable donations collected through the registers do not count as the store's income. Giving the lump sum to the charity does not count as a store expense. The store is merely a custodian of the money until transferring it to the charity.
• YOU get the tax deduction, not the store. If you itemize your tax deductions (and do not take the standard deduction), you can submit the register receipt as proof of a donation, and get the tax benefit.
• The media coverage of these donations for PR benefit is basically nil. Off the top of your head, name the last 3 feel-good stories about grocery store charity donations that you saw in the news. (Can you name even one? I can't.)
• Stores often do add some of their own money to the donation, but charitable donations are an "above the line" adjustment to income, not a "below the line" refundable credit. That is, the value of the write-off is the amount of tax the store avoided, which is always less then the amount of money it gave.

Last time I was at a grocery, and the payment terminal asked my to round up, I did. I see it as a win-win-win. I win because I can feel good about donating, even if it was only 14 cents. The store wins by some of my good feelings transferring to it; as well, the people who run the store are human, and also want to feel good about themselves by helping a charity. The charity itself wins by getting a couple thousand dollars that it wouldn't have received otherwise. Despite my best intentions, I wouldn't have gone out of my way to donate to that organization, and absolutely would not have bothered to give a tiny amount like 14 cents. But every little bit helps, and a few cents each from hundreds people adds up. I see this as a frictionless way to do some good.

Source: Used to work at a family-owned grocery store.