What's the best way for a commerce to accept XMR but getting paid in fiat currency ?

I recently discover NowPayments which looks like a cool services but does not suit well with a Monero mindset. I understand that it will have some compromises for using a service like that no matter how serious the ones running it are. I was just wondering if their was a simple way for a commerce to be paid in euro/dollar or whatever currency is prefered and that the customer uses XMR without comprimising any information on his/her side.