New York - Ka-ching! The cash register might 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.

"The traditional cash register is heading toward obsolescence," said Danielle Vitale, chief operating officer of Barneys New York.

That the cash register is getting the boot is no surprise. The writing has been on the wall for a long time for the iconic machine, which was created in the late 1800s. The register was essential in nearly every retail location by 1915, but it now seems outdated in a world in which smartphones and tablets increasingly are replacing everything from books to ATMs to cameras.

Stores like smartphones and tablets because they take up less floor space than registers and free up cashiers to help customers instead of being tethered to one spot. They also are cheaper: For instance, Apple Inc.'s iPads with accessories like credit card readers can cost a store $1,500, compared with $4,000 for a register. And Americans increasingly want the same speedy service in physical stores that they get from shopping online.

J.C. Penney, a mid-price department-store chain, said the response by customers has been great since it started rolling out iPod Touch devices late last year in its 1,100 stores.

It's been a long fall for the cash register, which innovated retail as we know it. The first register was invented following the Civil War by a little known saloon owner. Before then, most store owners were in the dark about whether they were making a profit, and many suffered since it was easy for sales clerks to steal from the cash drawer unnoticed. But by 1915, cash registers were ubiquitous in stores, with more than 1.5 million sold by then.

More recently, stores have been looking for ways to modernize checkout. Since 2003, self-checkout areas that enable customers to scan and bag their own merchandise have become commonplace in grocery and other stores. But recently, there's been a push to go further.

As a result, companies that make traditional cash registers are racing to come up new solutions. NCR Corp., formerly known as the National Cash Register Co., was the first to manufacturer the cash register on a large scale.

Last year, the company that also makes ATMS, self-service checkout machines and airport check-in kiosks, launched a program that merges its software with the iPad. This allows store clerks to detach the iPad from the keyboard at the counter and use it as a mobile checkout device "Retailers have more flexibility and more opportunities to change the shopping experience," said Mark Self, NCR's vice president of retail solutions marketing.

Stores themselves are also taking their cues from the success of Apple Inc. The nation's most profitable retailer moved to mobile checkout in its stores in 2006.

Take upscale handbag maker Coach, which is using iPod Touch devices at half of its 189 factory outlet stores. The company also is testing them in a handful of its 350 regular stores.

The move has enabled Coach to start slimming down its registers to the size of small podiums, leaving extra space that is equivalent to three days of product and a display table for the average store, said Francine Della Badia, Coach's executive vice president of merchandising.

For its part, Wal-Mart is putting checkout in the hands of the shoppers themselves.

The retailer is testing its "Scan & Go" app, which can be used on Apple devices such as iPads, in more than 200 of its more than 4,000 stores nationwide.

The app, which is aimed at reducing long checkout lines, requires that shoppers pay at self-checkout areas. So as it tests the app, Wal-Mart also is expanding the number of self-checkout areas in its stores.

"Our goal is to give choices to all of our customers however they want to shop," said Gibu Thomas, senior vice president of mobile and digital initiatives at Wal-Mart's global e-commerce division."

AT A GLANCE

LAST KA-CHING: 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

SPEEDIER SERVICE: Retailers are responding to the increasing demands of shoppers, who are buying and searching on tablets and smart phones and are looking for a similar speedy service in the stores.

WAVE ON THE WAY OUT: Analysts believe that mobile checkout will become commonplace in the next two to four years.