Sure, you can hold accounts in multiple currencies. However, if you're a sole developer or small business bringing in low-six-figure revenues, you're probably going to want to take much of that revenue out of the company to pay its people on a regular basis. That in turn probably means transferring it to your primary bank account and converting the currency to your primary currency in the process, which will incur a conversion cost again. So holding accounts in several different currencies mostly helps if you expect to both bring in and pay out significant amounts in those same currencies, avoiding a round trip of conversion to and back from your native currency.