Some useful phrases - Germany

Actually, English does have formal and informal forms of address. YOU is equivalent (and related to), the French VOUS. The English informal is THEE/THOU (like the French or Italian TU). It's just not used much anymore, except in lingering dialects ("THOU" is still heard occasionally in places in England).

So when we use YOU to address everyone, we're just using the formal form.

Many times after I pay at a grocery store or shop, the clerk will say to me something like, "Schoenen Tag" except sometimes they also add a bunch of other words. What are they saying, and what should I say in response? Is there something polite I can say after I pay each time regardless of whether they say, "Schoenen Tag" or "Auf Wiedersehen" or whatever else they might say? I usually just say "Vielen Dank", but that doesn't seem quite right after someone says, "Beautiful day" to you.

Gleichfalls!

As demonstrated by James in Dinner for One.

Thanks!