U.S. retail gas prices continue to rise slightly.

CAMARILLO, Calif. - Gas prices continued to rise during the holiday shopping season. Gas prices rose about 4 cents per gallon nationwide compared to two weeks ago, industry analyst Trilby Lundberg said Sunday. The national average for self-serve regular was $2.27 per gallon on Dec. 1, according to Lundberg's latest survey of 7,000 gas stations across the country.