Calculating capital Gains/losses with Comsec, page-6

Nothing to do with being cheap

Using a detailed spreadsheet for each Company that you trade/invest with has several advantages:

If you buy and sell the same Company hundreds of times a year; you can 'match' specific sales against specific purchases

You can minimise your capital gains by always selling the most expensive parcel

You can maximise gains by always selling the cheapest parcel

Also, you can sell parts of several different parcels

I am not aware of any standard platforms that can do this; but may well be wrong

Disclaimer

Stating the bleeding obvious; when you sell on a certain date you can only 'match' against shares purchased on or before that date