You upload the spreadsheet from your broker with your list of transactions, then you upload the spreadsheet of capital gains calculations you made for previous years, and it calculates your capital gains, matching your buys and sells in a manner to take into account ATO's 50% CGT discount policy, and minimise the capital gains for this year.
I've been working on it, but I haven't uploaded it yet. If you're going to use it I can work on getting it online this weekend and get it up in a week?
Right now only commsec format is implemented - I don't have etrade or ANZ or nab trade so I don't know their formats. (if you give me a few lines of your broker's files I can implement it for you)
Alternatively you can also send me your transactions and capital gains list to my email and I can run it for you today or tomorrow and send you back the result but you have to make your own decision whether to send your financial information to a stranger on hotcopper....