While transacting in monero is laudable and doing the world a service, when you sell a product in one currency, but purchase that product in another currency, you're setting yourself up for foreign exchange arbitrage. That is not a fun experience from the service provider perspective.
Scenario a: your prices are above the Fiat price and people don't buy it from you
Scenario b: your prices are below the Fiat price, and people buy a lot of it from you.
You end up holding the bag, or having no transactional volume at all.
Xmrbazaar Even does auto currency conversion on the website, shows you the price and your local Fiat.