TSX and TSX-Venture have what's called Board Lots which specifies the number of shares each "lot" will have.  It's based on the price of the share.  They are defined as follows (taken from TSX.COM)

Board Lot
A standard trading unit as defined in UMIR (Universal Market Integrity Rules). The board lot size of a security on Toronto Stock Exchange or TSX Venture Exchange depends on the trading price of the security, as follows:

• Trading price per unit is less than $0.10 - board lot size is 1,000 units
• Trading price per unit is $0.10 to $0.99 - board lot size is 500 units
• Trading price per unit is $1.00 or more - board lot size is 100 units

So if you are trying to buy 675 or 2150 or any number not a multiple of the board lot, they have to sell it as an "Odd Lot", which takes longer and sometimes does not get filled.

At least that's my understanding and based on my trades, it seems to work when I work with the multiples specified.

Cheers!