Costco Wholesale Corporation (COST) reported a 7% increase in sales at stores open at least one year in August, boosted by higher gasoline prices and stronger foreign currencies.

A survey of analysts by Thomson Reuters forecast an increase of 4.2%.

Net sales were $5.9 billion for August, an increase of 9% from August 2009, Costco said in a statement.

Net sales for the 16 weeks ended Aug. 29 were $23.6 billion, compared with $21.9 billion a year earlier.