Its what you spend, not what you save

The upscale supermarket must require their cashiers to tell you what you "saved" with your member loyalty card, because they tell me every time.  But did I really "save" that much?  The receipt may tell me I "saved" $10 by buying three of Item X for $15 when it was Buy One Get Two Free.  And I did "save" that much if I would regularly buy one of Item X at the cost of $15.  But if I would even buy Item X on a regular basis, I would probably be able to buy it for $7.50 or $10 somewhere else.