@crown93 for tax purposes:
https://www.ato.gov.au/Tax-professionals/TP/Tax-time-toolkit-for-investors/?page=15#Capital_gains_tax_on_the_sales_of_shares_or_units
according to the ato 3 common methods are:
FIFO (first-in, first out)
LIFO (last-in, first-out)
HIFO (highest-in, first-out)...