Forrester Research predicts online retail sales will grow 12% this holiday season, the slowest growth to date but more than five times the tepid 2.2% increase the National Retail Federation predicts overall in November and December. Even with declining gas prices, time-pressed consumers often find it easier and cheaper to shop on websites, thanks to free shipping or offers such as Gap's flat rate of $7 to ship anything you buy from any of their brands.