The sales increase follows a rise of 6% last year.
Impulse categories, soft drinks and confectionery are up by 5.6% and 6.5% respectively, while alcohol has performed well: beer sales rose 14.7%, spirits 24.1%, wine 25.8% and cider 32.9%.
Other improving categories include pet foods, paperware, groceries and non-foods.
The group has announced that by the end of September around 300 of its stores will be involved in its Hot House retail standards initiative - up from the current level of 236.
Managing director Martin Williams said: “This is a direct reflection of the hard work and investment Landmark members have put in. Close collaboration with all our major suppliers has contributed to this fantastic performance, along with the success of our Hot House retail development programme.”