It's not the tipping culture that's invading Germany, it's the "begging for tips" culture. The worst kind. You buy a piece of bread at the bakery over the counter, pay with card, the card reader is begging for tips. This is exceptionally out of the ordinary, but I'm afraid there is not enough explicit resistance and there is still too much "looking up to the USA" happening so that the society might accept this idiocy as normal some day.
Charging a tip for to-go items is preposterous. When dining in, I will indeed tip, usually by rounding up to the next 5 or 10 euro increment for a group meal, or to the next 1 or 2 euro increment for single meals (e.g. during lunch hours near the office). But this is only if the service is actually good. If a restaurant makes me wait more than 30 minutes for a quick lunch, they will be paid exactly the amount posted on the menu.
