Groupon recently rolled out a free iPad-based payment system intended to replace small business owner’s cash register, signaling the Chicago-based start-up’s expansion beyond daily deals and a challenge to other mobile payment pioneers, like Square.

The new point-of-sale system, called Breadcrumb POS, targets retail

In this Thursday, Sept. 22, 2011, photo, employees at Groupon pose in silhouette by the company logo in the lobby of the online coupon company's Chicago offices. (Charles Rex Arbogast/AP)

merchants, salons, and quick-serve restaurants, allowing them to charge customers and accept credit card payments for a fee of 1.8 percent per transaction, plus 15 cents. Small business owners do not have to offer daily deals through Groupon to use the system.

Groupon joins several other mobile payment start-ups offering point-of-sale systems for small businesses, many of which fall within roughly the same range of credit card fees. Square charges 2.75 percent per transaction, but offers an option for businesses bringing in less than $250,000 to pay a monthly fee of $275 instead of a transaction fee. PayPal Here charges 2.7 percent per swiped transaction; Intuit Merchant Services charges $12.95 monthly and 1.75 percent per swipe, or, alternatively, a flat fee of 2.75 percent per swipe.

Groupon also offers Breadcrumb Pro, a premium version of POS with free updates and more features, like labor tracking, starting at $99 a month.

Since its 2012 acquisition of Breadcrumb, the start-up responsible for the app, Groupon has been gradually expanding the base technology to accommodate more industries. Previously, Breadcrumb POS was used primarily by bars and restaurants. In the same year, Groupon acquired FeeFighters, which used to compare fees for various credit card payment systems.