NEW YORK – Ka-ching! The cash register may be on its final sale.

Stores across the country are ditching the old-fashioned, clunky machines and having salespeople – and even shoppers themselves – ring up sales on smartphones and tablet computers.

Barneys New York, a luxury retailer, this year plans to use iPads or iPod Touch devices for credit and debit card purchases in seven of its nearly two dozen regular-price stores. Urban Outfitters, a teen clothing chain, ordered its last traditional register last fall and plans to go completely mobile one day. And Wal-Mart, the world’s largest retailer, is testing a “Scan & Go” app that lets customers scan their items as they shop.