Anecdotally, the bank often cannot tell you how much. It has come up multiple times on /r/personalfinancecanada that the bank isn't really sure or generates a few different calculations. I also worked for a mid sized Canadian bank where the advisors couldn't consistently do it either.
That seems odd given that you can walk into your branch any time and get a payout statement that will tell you a total outstanding number. The statement is valid for the next 30 days or whatever, and any fees or penalties are itemized on itβ anyone who has paid off their mortgage due to either windfall or sale will have gone through this process.