I have seen this movie three or four years ago, it was indeed catchy and entertaining; and it got stuck in my memory. The very well american produced movie should be released between 2004 and 2009.
I remember that the movie started with a girl doing her job as cashier (or waitress). She seemed very proud of herself that she is pictured at the beginning of the movie recalculating the bill of a person.
Later the villain takes out a gun (and changes the mark of bar's as "closed" on the door) to prevent new customers from coming. The villain threatened the people. I don't remember what was the purpose, but I think he wanted to meet someone in the bar.
There was a lot of shooting in the movie, it was bloody, and I remember that a lot of people got killed; there were one couple hugging each other and scared.
What was bizarre about the movie, is that no cops came, and all the movie happens inside in the shop (yes, there are no scenes outside the shop).