Lets get straight to the point. Supermarkets are just entities designed to separate you from your cash as efficiently as possible.
Take no notice of the slogans, "Every Little Helps", "That's why Mums go to Iceland", "Saving you money, every day" and so on..
Any real benefit to you, is purely coincidental and only serves as further PR for the supermarket.
Remember this next time you are in the milking trough.. err checkout.
The catch phrase is a lie, but its not all bad in Blighty. We could have the U.S. equivalent:
"Piggly Wiggly. Feeds your life.
It feels like home.
Down home. Down the street"
Which is just plain silly.
Or this one from Kroger stores, which sounds more akin to something you would do in a quiet lay by after dark:
"Let's go Krogering"