Little-known fact:

When a store asks if you would like to "round up" your purchase to the nearest dollar, keep this in mind.

Merchants have already made the donation to the charity. When they ask if you would like to donate to the charity (of their choice), what they are doing is asking if you would like to reimburse the merchant a portion of the donation they already made so you feel good about yourself.

Hold onto your hard-earned money. The big corporations make big donations. They don't need you to reimburse them. Save your money for #bitcoin stacking.