Nope, I'm a stingy person with trust issues. Who is to say that the cashier/teller/person at the window doesn't just pocket the money themselves and still charge the person behind you. Now there have been times that I have bought things for soldiers at places like restaurants, but that was face to face. I've also helped people out who were short changed at the register, again, face to face.
AKedit: I don't give money to bums, either. We have a guy in Wooster that is younger, good shape, etc and pan handles. He is perfectly capable of getting a job and I call BS on his "I have a family to feed" sign. He is just trying to sucker us into giving him free money because he is too lazy to get a job. Whenever I see him in town I drive up to the nearest fast food joint, grab a job application and bring it to him.