As Lynell mentioned, AirBNB will show pricing and charges in the currency of the potential guests. This of course works both ways. Australian guests booking overseas stays are charged in AUD, and thus avoiding the foreign conversions that most banks charge for overseas transactions.
HI @Jamie597 , did the currrency conversion create a problem for you or your guest? As @Simon237 says above, this is standard practice here on Airbnb so shouldn't create problems, except it might create misunderstandings...