Absolutely, you can list both a rental and a sale.
Unfortunately, Realestate.com.au does require that you have two listings, one under each category (unless you have a commercial premise).
All you need to do is create a sale listing and a rental listing within your account. If you would like to save time, once you've created your first listing, simply ask our friendly staff to make an extra copy of that listing within the account for you, so you won't have to fill everything out again. You can then make payment and we can get you live for both categories.