Retailers saw a 7.8 per cent decline in takings in July over the same month last year, dragged down by a 42.7 per cent decline in motor vehicle sales.
Excluding motor vehicles, retail sales went up 2.5 per cent.
Sales of telecommunications apparatus and computers, recreational goods and wearing apparel and footwear also decreased between 2.4 per cent and 7.0 per cent in July.
Food and beverage services performed slightly better, recording a 2.1 per cent rise over the same month last year.
Compared to June, retail sales in July were 5.3 per cent lower, again on the back of a 19.7 per cent decline in motor vehicle sales.