T-Mobile USA announced on Tuesday that it is now selling Square credit card systems in its retail stores. Square allows people to take payments by swiping a credit card through the Square dongle, which can be plugged into the end of a smartphone. “The success of our small business customers is important to us. Formerly ‘cash only’ small businesses can now simply and cost-effectively accept credit cards with their smartphone using Square, giving them an easy path to growth,” said Matt Millen, vice president of small and medium business sales at T-Mobile. “As these businesses evaluate their wireless needs, T-Mobile is committed to providing quality of service, cost savings and connectivity that are a requirement for their success.” T-Mobile will also