Simple pricing. No need for a calculator. And then you quote prices in swiss franks instead of US dollars as its common in hosting industry. I don't have currency converter in my head nor I know USD->CHF rate
https://www.google.co.uk/webhp?#q=1%20chf%20in%20usd
https://duckduckgo.com/?q=1chf+in+usd&ia=currency
http://www.wolframalpha.com/input/?i=1+chf+in+usd
If they are charging in CHF, then it's in both their and their customers' interests to quote in CHF, otherwise fluctuations in currency markets and variations in the exchange rates offered by their customers' banks will invalidate those quotes.