May I pay tolls in euros instead of Swiss Francs? May tolls be paid by credit card?
There aren't toll roads in Switzerland. Instead, as you enter the country you have to pay a 27 Euro annual road permit fee and they give you a sticker for your car. That allows you to drive on their highways.
If you're renting in Switzerland, check that your car already has the annual sticker.
In countries where there are toll roads like France and Italy you can pay with credit card.
When we entered Switzerland from Germany we didn't have Swiss Francs, but no problem, they took credit cards, euros and even US dollars.
When buying something in Switzerland with money other than the Swiss Franc, the shop owner will likely offer a poor exchange rate. He/she is not a bank and will probably not know the day's exact rate. To protect themselves shop owners must use a rate of exchange that safe guards themselves from losing money. If you do not have Swiss Francs, use your credit card.