The United States <a href="http://mojepozivnice.com/?attachment_id=709">best rx promotions</a>  Sales at stores open at least a year, a retail metric knownas same-store sales, show that Costco has an edge. Costco's U.S.same-store sales rose 5 percent last quarter. Sam's Club'ssame-store sales rose 1.7 percent last quarter and it expectsthem to be flat to up 2 percent this quarter.