NEW YORK (CNNMoney.com) -- Consumers pulled out their wallets and hit their favorite discount and department stores in May, helping retailers post their ninth straight month of increasing sales.
According to sales tracker Thomson Reuters, which looks at monthly same-store sales for 28 leading chains such as Macy's (M, Fortune 500), Target (TGT, Fortune 500), Costco (COST, Fortune 500) and J.C. Penney (JCP, Fortune 500), May sales rose 2.5%, coming in slightly below the firm's initial estimate for an increase of 2.6%.
Same-store sales, a key gauge of a retailer's performance, measure sales at stores open at least a year.
May's 2.5% increase was a big jump from April's small bump of 0.5%, and it was a significant improvement from the 4.8% sales decline retailers posted for the same month a year ago.
Of the 28 stores, 63% beat analysts' expectations, while 37% missed.
Among the best performers last month, discounters posted the largest increase, rising an average of 5.3%. Costco led the way with a 9% rise in May sales, but that increase was slightly below analysts' forecast for an increase of 9.7%.
The company said that higher gasoline prices and stronger foreign currencies pressured sales.
Sales at discounter Target rose 1.3% last month, slightly better than expected.
In the department store arena, Macy's logged a same-store sales gain of 1.4%.