I hear this claim every now and then. That US currency is legal tender and that it is illegal to not accept it.
The most recent example of this was on an old episode of 30 Rock: The head and the hair.
I was not able to find a clip online, however I did find this transcripttranscript.
Cashier: No $100s, Small bills.
Liz: Oh, I knew this was gonna happen.
Cashier: Store policy.
Liz: Yeah, Well, That's an illegal policy. You have to take this.
Cashier: No, I don't
Gray: Yeah sir you do, it says "legal tender for all debts, public and private."
Cashier: Does it say anything about $100 for a bottle of water?
Gray: You can't decide what money you'll accept. That's illegal.
Is this claim accurate?