U.S. retail sales, excluding automobiles and gas, had grown 5.5 percent in the period between Black Friday and Christmas Eve last year. Online sales grew 20 percent in the holiday season this year, MasterCard Advisors, which tracks customer spending, said in a report on Monday. “The double-digit growth in furniture sales … shows that consumers are willing and able to splurge on big ticket items,” Sarah Quinlan, senior vice president of Market Insights at MasterCard Advisors, said in the report.