Retailers capped the holiday season on a cheery note as a last-minute buying spree lifted December sales well above views, causing many chains to up profit forecasts on Thursday. Overall December sales at stores open at least a year rose 3% vs. December 2008, said Ken Perkins, president of Retail Metrics. That easily beat Wall Street's forecast of a modest 1.8% gain. It was the biggest monthly rise since April 2008. A hefty 72% of retailers topped