Retailers capped the holiday season with December sales that beat views overall. But the showing Thursday was a mixed bag with retailers on the high end and low end faring well and those in the middle posting disappointing results. Sales at stores open at least a year rose 4.8% vs. a year earlier, says Ken Perkins, president of Retail Metrics. Analysts forecast a rise of already-lowered views for a 3.4% increase. Fifty-three percent beat