Dozens of U.S. stores at retail giant Walmart have begun offering bitcoin ATMs for customers to buy bitcoin, CoinDesk reports. Bitcoin ATM company Coinme and ATM equipment provider Coinstar have teamed up to launch a pilot that will allow customers to buy bitcoin with cash, and 200 ATMs in U.S. Walmart stores are part of the pilot. The ATMs will charge a 4% fee for bitcoin exchanges, plus a 7% fee for cash exchanges.