Higher gas prices, foreign currency, and an increase in traffic resulted in an 8 percent increase in total company comps for Costco Wholesale Corp. Same store sales at its U.S. locations alone increased 7 percent, with international comps up 14 percent.

Food helped drive comps. The retailer said during yesterday's earnings call that it benefited from some inflation on the food side, as a result of the recent run up in the cost of commodities.

Costco's sales for the four weeks ending May 4 were $5.54 billion, an increase of 12 percent from $4.94 billion last year. Year to date sales were $46.88 billion, also up 12 percent from $41.90 last year.

Costco operates 536 warehouses, including 392 in the United States and Puerto Rico, 75 in Canada, 19 in the United Kingdom, six in Korea, five in Taiwan, eight in Japan, and 31 in Mexico.