* Foot traffic also rose 2.5 pct-ShopperTrak * Heavy discounting late in season brought in shoppers By Phil Wahba Jan 9 (Reuters) - U.S. retail sales rose 2.5 percent during the 2012 holiday season, helped by a late surge in shopping trips right before Christmas, retail tracking firm ShopperTrak said on Wednesday, the latest sign that retailers had a solid but not great season. ShopperTrak, which monitors the number of people walking into stores across the United States, said foot traffic also rose 2.5 percent in November and December. After a strong start to the season over the Black Friday weekend that follows Thanksgiving, U.S. shoppers held off from buying, waiting for deals and weighed down by concerns about the prospects of higher taxes in 2013. In mid-December, after seeing a slowdown in retail sales after the season got off to a strong start, ShopperTrak lowered its forecast, calling for sales to increase 2.5 percent from 2011, compared to an earlier forecast of a 3.3 percent jump. The Saturday before Christmas, nicknamed "Super Saturday" in the retail industry, was the second busiest day in terms of holiday season sales after Black Friday in 2012, according to ShopperTrak. "The procrastinators held out until the end," ShopperTrak founder Bill Martin told Reuters. That in turn led to heavy discounting at the end of December to bring in shoppers. Retail sales rose 18 percent in the week that ended Dec. 29 compared to a year earlier, ShopperTrak said. Last week, Kohl's Corp said that its sales came late in the season and its discounts were deeper than planned. Macy's Inc had strong December sales but lowered its quarterly profit and sales forecasts. Trends show individuals proved willing to visit more stores in search of deals, a behavior that can also help retailers since it can lead to more impulse buying, Martin said. The National Retail Federation, which will publish its holiday sales results next week, has forecast an increase of 4.1 percent. A SpendingPulse report by MasterCard Advisors on Wednesday found that excluding car sales, but including gasoline, groceries and restaurants, U.S. retail spending rose 2.4 percent in December, a slower pace than the 4.5 percent rise in November. "The lack of (consumer) confidence brought growth down," said Michael McNamara, MasterCard Advisors' global solutions leader, also noting that the surge in sales after Christmas was prompted by bigger deals this year.