Square unveiled a new piece of hardware on Tuesday, designed to replace traditional cash registers in the businesses that use the company to accept payments. Square Stand, which can be pre-ordered for $299 starting today, features an integrated card reader for processing payments. An iPad connects to the stand, and the payment software runs on iOS. The stand connects to receipt printers, barcode scanners and other peripherals. It will become available in July online and at traditional retailers including Best Buy. Jack Dorsey, Square’s co-founder and CEO, said the stand marked an improvement on clunky point-of-sale systems that have dominated sales counters for decades. Merchants are fed up with existing solutions, he said. “They have to deal with these ugly systems that they don’t know how to use,” Dorsey said.