NEW YORK, United States — US holiday sales rose a less-than-forecast 3 percent, the National Retail Federation said, as merchants coped with unseasonably warm weather and a shift to spending on services.Holiday spending, which the group had projected to rise 3.7 percent, grew to $625.9 billion in the period, which spans November and December. Non-store sales, an indicator of e- commerce transactions, increased 9 percent to $105 billion, the NRF said. The figures exclude spending on automobiles, gasoline and restaurants.Retailers faced with mild weather and high inventories slashed prices to lure shoppers in the 2015 holiday season. As consumers shifted spending to experiences and services, such as restaurants, shows and nail salons, more retailers added promotions like free shipping.Research firm First Data said this month that retail sales increased 3.3 percent from Oct. 31 through Jan. 4, up from a 3.2 percent gain in the year-earlier period. The Thanksgiving holiday weekend dominated spending in the period, with sales rising 6.3 percent, the firm said, while the last two weeks of December also showed a higher concentration of sales.By: Lindsey Rupp; editors: Nick Turner and Mark Schoifet.