Although not technically an answer to your question, I want to address why this is generally a bad idea.
People normally put money into a savings account so that they can have quick access to it if needed, and because it is safe. You lose both of these advantages with a foreign account. You are looking at extra time and fees to receive access to the money in those australian accounts. And, more importantly, you are taking on substantial FX risk. Since 2000 the AUD exchange rate has gone from a low of 0.4845 to a high of 1.0972. Those swings are almost as large as the swings of the S&P. But, you're only getting an average return of 3.5%, instead of the average return people expect with stocks of 10%.
A better idea would be to talk to a financial adviser who can help you find an investment that meets your risk tolerance, but gives you a better return than your savings account.
On a final thought, the exception to this would be if you plan on spending significant time in Australia. Having money in a savings account there would actually allow you to mitigate some of your FX risk by allowing you to decide whether to convert USD when you are travelling, or using the money that you already have in your foreign account.