The Provinces are going to set their own tax rate on the sale of cannabis, so there won't need to be any "knocking".

Some Provinces, such as Ontario, are likely to also implement "hidden" taxation on the sale of cannabis by means of restricting exclusively distribution to a government-run organization (Ontario could charge $0 "tax" and $10 "profit" and the result would be exactly the same as $5 "tax" and $5 "profit" or $10 "tax" and $0 "profit).