Unhöfliches Kassenpersonal

Hi, at the Rewe at Dorothen str. as well as at the one at Golbekplatz would someone be so nice to suggest some of the the cashiers to treat all customers equally polite? I mean for instance saying "hello" to everyone, even if they look foreign. I do not look much German but I do understand if you guys say "Danke" or "Hallo" to everyone but skip me and I do not find it nice, so I suggest especially the cashiers to pay attention on this.