The company said that, for the 12 weeks to 22 February 2015, the average value of an order was down 2.5% to £114.72, but the average number of orders had increased 18.1% to 183,000.
Tim Steiner, chief executive, said: “Our business continued to grow, against the backdrop of a retail market that remains challenging and competitive.
“We remain committed to improving the quality of the proposition to customers, which we believe will support further growth.
“Notwithstanding the uncertainty that remains in the marketplace, we expect to continue growing slightly ahead of the online grocery market.”
Gross retail sales for the group were up 15.2% to £252m for the 12-week period.