Iowa's gas prices are up slightly from last week. Minnesota-Iowa Triple A says the price for a gallon of regular unleaded is up a penny from last week. The statewide average is $2.74, still well above last month's $2.60. Sioux City has Iowa's cheapest gas at $2.67 a gallon, while Dubuque and the Waterloo-Cedar Falls area are tops at $2.80. The national average is $2.89.