You might have heard of businesses that have stopped taking cash. Paying by credit card or plastic is becoming the norm, even as dollar bills are defined as “legal tender for all debts, public and private,” according to Slate. The Federal Reserve measured the amount of actual physical cash (M0) at $688 billion in 2004, according to Wikipedia. The Coinage Act of 1965 specifies that cash, excluding foreign gold or silver coins, is legal tender for the payment of debts, public charges, taxes and dues, according to Slate. The word “public” is key in this sentence though.