U.S. retail sales slipped during the week that ended Saturday, a Washington retail trade group said. It was the second consecutive week-to-week drop in sales receipts, the International Council of Shopping Centers-Goldman Sachs weekly consumer tracking survey said. Sales receipts slipped 0.7 percent after falling 3.1 percent in the previous week. From the same week of 2011, sales were up 2.5 percent. Retailers could be encouraged by a consumer survey in which 51 percent of respondents indicated they had completed their holiday shopping, while 55 percent indicated by this week of 2011 that they were done with their gift shopping. \"With only two weeks left to complete holiday shopping ahead of Christmas Day, consumers will likely step up their pace considerably by this coming weekend,\" the ICSC-GS report said.