Sweden’s currency is the Swedish krona. Tourists in Sweden often assume that we use the euro. Regarding online pricing, there is also often a misconception that all European Union countries have adopted the single currency. I am not sure if PayPal even offers SEK (Swedish kronor) as an option from the US.
Apart from Denmark (which has an opt-out for the single currency but is pegged to the euro), all EU member states are – in principle – obliged to introduce the euro once they fulfil the four convergence criteria. In theory, Sweden probably fulfils all the criteria (inflation rate, government deficit/debt-to-GDP ratio, interest rate, and membership of the ERM), but I doubt the EU would try to force Sweden to join the single currency. Sweden is a net contributor to the EU (pays in more money than it gets out) and the EU may not want to risk a Swexit.
Being in the Eurozone makes commerce so much easier, no conversion rates and exchange rate fees.
I voted yes to the euro in the referendum but it went to a no. It was non-binding but the government decided to stay out of it for now. At the moment the Swedish krona is REALLY weak. So cheap for you to visit us, though we do have a level 4 of 5 for terror attacks at the moment 🙁