I am currently analysing an ecommerce site specialised in Catering in Poland. I am thinking about suggesting sales department changing the payment format from PLN to EUR, but I am wondering how is the users perspective on that?
You could consider displaying both currencies, like in my example below. This way you won't confuse your customers.
On the check-out page you could the exact same thing with the round up of total costs displaying in both Zloty and Euro.
Another option is to let users choose their currency. Large international ecommerce websites do the same thing.
I will first talk to some real end users and see what their preference is. Or if there is a way you can check which currency they paid in recent past, you can understand which currency end users are most comfortable with. It's always better to test than assume.
Having said that if you find users generally want to see Euro as well as PLN, I suggest you have a global option to switch currency. Just like the country selector you already have there up top. This way a user can switch to their preferred currency. Then you can use a cookie to set users preferred currency when they return to the site. But make sure you still have the currency switch visible.
An alternative is to show the amount in PLN on hover over. But this option you need to make sure most users prefer Euro and only minor percentage of users require amount in PLN.
I’d do the user research first and find end user preference.
User preferences aside, since Poland does not use EUR as their official currency it would be no good idea restricting all prices to a foreign currency. If you considing using EUR values to make it easier for travelling or international users (like a customer that would like to host an event in Poland, without actually being from there), I suggest to offer a global currency switcher on the website.
Show prices in: EUR / POL
Put the switcher somewhere in the site's header to allow the user to change and check the setting anytime. Not to be forgotten that the website might get more international reception.
I would suggest not to change it at the moment. Poland are still using Polish Zloty, and it will be confusing for a regular person that has Zloty in his bank account to see Euro.
The exchange rate is 1:4.20 so every time a person buys something they have to multiply the Euro balance by Zloty.
The idea is to make it easier for your client not harder.
Another way is to display both, thats what they do in high end shops.