To a large extent it matters not what your broker does behind the scenes to acquire the stock for you. When you buy or sell a given parcel of shares your broker will give you a contract note indicating the quantity of stock traded and the cost per unit, brokerage, GST etc. This document is what you use for calculating your gain / loss for tax purposes.
If your broker plays silly buggers in the background for his / her own ammusement and / or gain, it matters not to you unless you instructed them to do as such and they provide your with dozens of separate contract notes upon completion of the exercise.
CDU Price at posting:
$3.10 Sentiment: Buy Disclosure: Held