Costco Wholesale Corp., the membership club retailer with six stores in Hawai'i, said its June same-store sales rose 9 percent in the U.S., helped by rising gasoline prices.

The company said excluding gasoline, its sales at U.S. stores open at least a year rose bny 5 percent. Retail analysts said part of the increase comes as shoppers turn away from some luxury stores and look at discount chains.