That argument about multiple level taxes is always beyond me. Taxes are not stock market which changes in unknown direction constantly, they are always known at the worst weeks before implementation.
In my eastern European country even biggest supermarkets can change all labels overnight (I even bet they can can do at least twice daily - albeit with here and there confusions when there multiple labels for same good)
And western European one have e-ink price tags. And one time there was wrong item on a tag. So I asked the person filling the shelf for help. He read the tag and item and behold in 5 minutes it updated itself to correct item and price...
It is not like these shops hop hourly between taxes...
In my eastern European country even biggest supermarkets can change all labels overnight (I even bet they can can do at least twice daily - albeit with here and there confusions when there multiple labels for same good)