REUTERS/Suzanne Plunkett
Economists were expecting a 5.9% jump year-on-year in January, but a 0.2% drop from December's levels.
December and November's retail sales were particularly strong, driven by Black Friday madness and the beginning of Christmas shopping.
Analysts will also be looking out for the effect that falling petrol prices have on the sales figures: Are peoples' savings on fuel being driven in to other sectors?