Now almost all of Wal-Mart’s 4,700 U.S. stores have a Cash360 machine, making thousands of positions obsolete. Most of the employees in those positions moved into store jobs to improve service, said a Wal-Mart spokesman. More than 500 have left the company. The store accountant displaced last August is now a greeter at the front door, where she still earns $13 an hour. “The role of service and customer-facing associates will always be there,” said Judith McKenna, Wal-Mart’s U.S. chief operating officer. But, she added, “there are interesting developments in technology that mean those roles shift and change over time.” Shopping is moving online, hourly wages are rising and retail profits are shrinking—a formula that pressures retailers, ranging from Wal-Mart to Tiffany & Co., to find technology that can do the rote labor of retail workers or replace them altogether.