Topshare's View CG Liability form conveniently allows you to assess the capital gains situation for any of the shares in your portfolio.
Once you have selected a stock from the portfolio holdings, all parcels are displayed:

Now, simply select the parcel to see the CG details. An example for Simsmetal is shown. In the panel on the right of the form, you can see you'll receive a net benefit of $1,303.90. With this particular combination of purchase and sale dates, both the CPI-Indexation and the 50% Discount rules apply for Capital Gains Tax.
Topshare calculates the assessable Capital Gains according to both rules. In this case, the 50% Discount rule clearly produces the best outcome, with an assessable CG of $651.95 - compared with $1,200.96 if assessed according to the CPI-Indexation rule.