NEW YORK, Jan 6 - Post-Christmas promotions dragged on U.S. chain store sales, but retailers reported moderate business across broad channels, Redbook said in a report on Tuesday. The pace of sales at major retailers grew by 3.4 percent on a year-over-year basis for the week ended Jan. 3, slowing a touch from 3.9 percent the preceding week, the report said. Sales ended December down 1.0 percent when compared to November. Store traffic remained high, even in the period following Christmas, but tight inventories kept some shoppers from finding what they wanted, the report said. Also, many shoppers decided to hold on to their gift cards for future use, delaying the time when retailers could book those sales. The Redbook data are compiled from a sample of same-store sales at general merchandise retailers representing about 9,000 stores. Same-store sales measure revenue at stores open at least one year.||www.reutes.com