Ouch, Neil! I didn't mean to upset your weekend. I was trying to be helpful in pointing out a title correctly priced ... from a consumer's point of view, too.
The $6.19 Kobo price in Canada is likely the US$5.95 list ... so both booksellers have it for the same list. But Kobo has a 20% sale ... isn't that ok? Amazon has the opportunity to put the titles on sale if it wants to, doesn't it?
The general consumer expectation is books (and ebooks) are bought at a discount from list. If your intention is to sell everything at $5.95 all the time ... it will never "feel" like a deal and the sense of urgency to buy this today is lost. It seems to me a much better strategy to price all the books at $7.50 list but always sell them at $5.95 if that's the margin you are looking for.
A second issue in the pricing to consider is whether the consumer is willing to pay a premium from one vendor or another. I'm a great supporter of Kobo and have bought several titles. But the formatting isn't always as good as the Kindle (I have some dual purchases to prove it) and, well, I prefer reading on my Kindle. I buy Kobobooks because there is content I can't get elsewhere, and sometimes I get a bargain -- like the recent Man Booker winner, The Finkler Question, which I bought at Kobobooks.
So, streamline the list prices, control the sale prices if you must, but consider a built-in discount, too.