Canada's retail sales in December grew by a robust 2.5% on a monthly basis, beating analysts' expectations, as a sales tax holiday bumped up spending on food and beverages and people also bought cars and vehicle parts, data showed on Friday. Retail sales in December are usually higher due to the holiday season. Economists said the government's sales tax break, which kicked off in mid-December and ended February 15, also boosted revenues. Analysts polled by Reuters had forecast retail sales would rise by 1.6% on a month-on-month basis and by 1.8% excluding automotive and parts sales.