Sales fell after five consecutive monthly gains. Sales slid 0.9 percent excluding the volatile category of motor vehicles and automotive parts, the data agency said.
A 6.4 percent sales decline at new car dealers led the downturn. Sales at new car dealerships fell 7.7 percent in the month. Sales of automobile accessories and tires also fell.
Holiday shopping was also slow. "Most store types typically associated with holiday shopping registered weaker sales in December," the report said.