Before computers it was somewhat more convenient, albeit not worth the price. Now, after computers, a reserve currency is wildly superfluous. The only reason to accept a reserve currency is to donate money to another country's central bank. "I love inflation and can't get enough."
Simply have the computer convert all prices to the local currency and include the conversion costs without telling you, since you don't need to know. Maybe get a programmer to make it handle tariffs and such as well.
The only reason USD survived as 'reserve' is because everyone knew they would go all Ukraine on you if you were the first to stop clapping. Now they've a) blown their wad and b) shown that the threat was in fact impotent.