File photo of re-useable Walmart bags are seen in a newly opened Walmart Neighborhood Market in Chicago

 
File photo of re-useable Walmart bags are seen in a newly opened Walmart Neighborhood Market in Chicago
Re-useable Walmart bags are seen in a newly opened Walmart Neighborhood Market in Chicago in this September 21, 2011 file photo. Wal-Mart is now pushing its grocery suppliers harder to offer consistently low prices, instead of timed promotions or "rollbacks." That means food companies are unlikely to be able to pass through more price increases and will be forced to pull other levers, such as cost-cuts to protect margins or product innovation to drive sales, as reported March 6, 2012. Picture taken September 21, 2011. REUTERS/Jim Young/Files (UNITED STATES - Tags: FOOD BUSINESS)