ISSAQUAH, Wash. ( TheStreet) - Costco ( COST), the warehouse retailer, said November comparable-store sales rose 6% in November and 4% in the quarter ended Nov. 29. Comparable-store sales in the United States rose 2% in November; international same-store sales were up 21%. Analysts surveyed by Thomson Reuters estimated November same-store sales would increase 8.1%. Costco, in a press release Thursday, said net sales in November rose 9% to $6.04 billion. Quarterly net sales gained 6% to $18.57 billion. Costco said inflation in gas prices, as well as a weaker U.S. dollar, had a positive impact on November's comparable-store sales. Excluding these factors, comparable-store sales rose 2%, but were flat in the United States. -- Reported by Joseph Woelfel in New York . Follow TheStreet.com on Twitter and become a fan on Facebook.