The loonie was down 0.3 of a U.S. cent to 79.71 cents after Statistics Canada reported that sales fell two per cent to $42.1 billion, the largest one-month decline since April 2010. Economists had generally expected a dip of 0.4 per cent.
Declines were led by a 7.4 per cent slide in sales at gasoline stations, reflecting sharply lower fuel prices.
Performance was also impacted by a one per cent drop in sales at new car dealers.
The biggest increase came from food and beverage stores, up one per cent.
Meanwhile, Greece and its eurozone partners came to an agreement to extend by four months the country's bailout loans that have kept the country afloat
An official close to discussions by eurozone finance ministers said that, as part of the agreement, Greece could "present a first list of reform measures by Monday" for the country's debt inspectors to assess.
European creditors have insisted that any extension to loans should be accompanied by a commitment to some budget measures and reforms.
Greece's current bailout program is due to expire Feb. 28. In the short term, if no solution were found, Greece could be left to handle its debts alone starting next month.
The sticking point has been that the proposal from Greece's new government did not promise to continue all of the budget cuts and reforms that the eurozone has demanded as a condition for past bailout payments.
Oil prices continued to decline in the wake of the latest data showing sharp rises in American inventory levels. The April contract in New York was down $1.02 to US$50.81.
Metals were lower with March copper off three cents to US$2.59 a pound while April gold faded $2.70 to US$1,204.90 an ounce.