Use Groupon Payments for your business? You just got a little more choice -- the popular deal broker just updated its Android app to support credit card transactions. The update brings the fledgling payment service a little closer to Square, which has been available on Android since 2010. If the iOS rates hold, swiping plastic through Groupon Merchants will set retailers back a mere $0.15 per transaction, plus 1.8 percent of the charge for Visa, MasterCard and Discover, or three percent for American Express. The update also boasts improved analytics, giving retailers the ability to check transaction history, daily sales reports and peek at revenue trends.