Overwhelmed by check-out-line charity  Charity coupons in a
check-out line at a Whole Foods store in New York City.   Kai
Ryssdal: Tell me if this has happened to you recently at the
supermarket. You unload your basket onto the conveyor belt,
browse the tabloids as you wait for the cashier, and then that
cashier hits you up for a donation while he's ringing up your
groceries. It's tough to get through your shopping these days
without being asked to give to one thing or another. A dollar
here and a dollar there can really add up for what are often
worthy causes. But Michael May explains that there are some
hidden costs.  DAVID FICKECK: Would you like to make a donation
to the KEYE food drive today? They're a $1, $5 donation, or you
can pick a bag over here we can gladly scan for you.  That's
David Fickeck, a cashier and store director at the Randall's
supermarket in Austin, Texas. He does more than ring up
groceries. He's a fundraiser.  Randall's supermarket is owned by
Safeway, which does four national charit