Updated from 10:35 a.m. EST

Retailer J.C. Penney ( JCP) said same-store sales were ahead of its low-single-digit growth plan for December, because of strong sales last week.

The Plano, Texas-based company said December sales in the first two weeks of the month were above plan, while in the last week, J.C. Penny's sales were strongest in its jewelry, shoes and children's categories.

The company also said sales in its Eckerd pharmacy stores are expected to increase 6% and that catalog same-store sales will decrease 20% for the month.

Shares of the company closed 3 cents higher, to $23.04, on the New York Stock Exchange .