To add some context: The food market in Germany is very competitive. I doubt there are any margin or a need for Groupons of any kind.
The US is not even close to what is going on in Germany. I compare the situation with gasoline, it's just the other way around. Unfortunatly I cannot back this up with any reference, but you would believe it after just walking through a supermarket.
I don't know how positive a picture this really paints. They had the uptick in the last quarter, but it's overall trending downward pretty seriously.
Ask HN: How do you say "Geiz ist geil" in English?