So 5% of outstanding stock is 19.4 million shares.
So buyback will be somewhere north of $20 million AUD.
Average daily volume across NZ & ASX trading for MHJ is 140k per day (29k on NZX, 111k on ASX).
19.4 million sahres bought back across roughly 250 trading days in a year = 77.6k shares repurchased each day, or over 55% of the current average daily trading volume.
Seems like it is going to have quite a substantial impact.