Brokers don't pay commission on trades like that - they pay a percentage fee on total cost of trades - direct access to the ASX system and all that. They aren't using Etrade.
The small bites could be part of an accumulation BOT, or someone trying to support the price (for many reasons including allowing a sufficient level of buyers to build up before selling into them. You can't really tell.
I bought in yesterday on price of silver heading over $20 and hopefully a Santa rally.
CCU Price at posting:
10.5¢ Sentiment: Buy Disclosure: Held