This assertion is wrong. If the item you buy is $1.00, then after your 14% tax it will be $1.14, which is rounded up to $1.15. If the item is $2.00, then after tax it is $2.28, which also rounds up to $2.30. But if the item is $3.00, then after tax it is $3.42, which rounds down to $3.40. If the item is $4.00, then after tax it is $4.56, which rounds down to $4.55.
Secondly, the rounding to nearest nickel is done per transaction, not per item. So if you go to a supermarket and pick up 3 items costing exactly $1.00, then the total you owe is $3.42 (which becomes $3.40 in cash), and it is that amount that is subjected to rounding, not the individual items (which are $1.13 and would round to $1.15).
I live in Toronto and have analyzed my retail receipts. (I'm aware the HST is currently 13% but that's not relevant to this argument.) The rule about rounding to the nearest nickel is sensible enough, but I've witnessed various weird behaviors. For example, each vendor has a different kind of wording to show how they rounded your cash transaction. Some use a negative sign to show that the penny rounding deducted money from your total owed, while some use a negative sign to show that the penny rounding increased your total owed (as if you paid negative money). Also, a few vendors always round down to the nearest 5 cents (to appear nice to the customer), which causes a surprise when I'm trying to prepare the correct amount of change. Finally, some vendors don't display cash rounding on their receipts, so for them it is an oral culture that isn't formally written down.