In May, sales rose 1.9 percent to $40.4 billion.
In the first half of the year, retail sales were up 1.8 percent compared to January through June of 2012, the data office said.
By volume, retail sales fell 1.2 percent in June after three consecutive monthly increases.
StatsCan said flooding in southern Alberta and a labor strike in Quebec weighed on sales for the month, which look particularly off, given the sharp gains from the previous month.
By economic value, the largest decline was posted by food and beverage stores with a 1.2 percent drop. That included a 0.9 percent drop at grocery stores, a 2.1 percent decline at liquor stores.
Building materials and garden equipment sales fell 1.9 percent in the month for the third decline in four months. Clothing sales slipped 2.3 percent and shoe store sales fell 2.4 percent, the agency said.
Sales rose slightly, up 0.2 percent, at automobile dealerships in the month, the sixth consecutive monthly increase. Sales at new car dealers rose 0.7 percent, which offset a 2.7 percent decline in sales of auto parts, a 1.7 percent drop at used car lots and a 1.1 percent drop at other vehicle dealers, StatsCan said.