Costco (NASDAQ:COST) saw its net sales for July rise 7% to $7.87 billion over the $7.36 billion for July 2012, the company announced today. However, same-store sales rose just 4% for those periods, disappointing analysts who had expected a 5.1% increase.

The company accounted for the discrepancy with the negative effect foreign exchange rates had on comparable sales, though that was partly offset by the positive impact of gasoline prices.

Discounting the effects of exchange rates and gas prices, the same-store sales would have increased 5%, according to the company.

For the 48 weeks ending Aug. 4, 2013, net sales increased 8% to $94.91 billion, from $87.72 billion for the same period ending Aug. 4, 2012. Same-store sales for that same 48-week period were up 6%, compared to the same period in 2012.

Costco operates more than 600 warehouses in countries including the U.S., Canada, Mexico, the United Kingdom, Japan, Taiwan, Korea, and Australia. It plans to open up to two new warehouses prior to the end of its fiscal year on Sept. 1.