The survey partners said overall figures, though down by 0.3%, were among the best in recent months.
But that was largely due to a better performance by non-foods including clothing, beauty products and products for outdoor activities, all thought to be helped by decent weather during the month.
Non-food sales almost held up to the same level they achieved in the same month the year before.
But food sales values were down by 0.7%, in part because they are being hit by declining prices.
“Grocery sales continue to be weak, posting a real terms fall once food price deflation is accounted for,” said David Lonsdale, director of the Scottish Retail Consortium.
“The three-month average for food sales continues to be negative, highlighting how challenging the food retail market is,” he added.
