Normally, when merchants calculate their price tags, they add credit card charges ( 1.5%-2% most from VISA/ MS) as a cost. The Retail Council of Canada has been fighting with credit card providers to lower their fees for a long. Credit cards in Canada are charging merchants the higher fees in the developed world:
The Cost to the Retailer
For a $500 transaction – the cost to the retailer can then range from:
Cash: $0
Debit: $0.10
Credit: $10
The more people who use credit cards – the more expensive the cost to retailers andthe higher prices become for everyone.
If merchants charge you fees for paying by credit cards, they must indicate it clearly when paying, otherwise, it is against the Consumer Protection Act and you can complain to Consumer Protection Ontario.
BTW, I don't believe all retailers will charge customer credit card fees.