We do have a feature in CAPITAL 7.4 or above that allows you to report in a base currency, such as Australian dollars, and simultaneously report in other currencies as well.
This would be useful if you needed to maintain assets and liabilities in different currencies simultaneously. This is used when you have a business in one country but then need to report back to a 'head office' in another country, typically on a monthly basis.
On the other hand you may not really require such powerful features, as you could manually translate $AUS values into $US dollars by printing reports from your accounting software in local dollars and then using the end of month exchange rate to translate that into US dollars. The software you choose should probably allow you to export to Excel so that you could perform such calculations. So the question is, is this something you would want to do manually each month or something you'd prefer the software to automate for you? You also need to consider what your knowledge of accounting and accounting software is and if you could set this up all your self or your budget allowed you to bring a consultant in for a day or two and set-up the software correctly for you. This is because multi-currency general ledgers are regarded as 'advanced' features that usually requires an expert to help you with on set-up, unless you already have a lot of experience setting up accounting software.