It's been decades since I sold a property using the services of a realtor. But in British Columbia at the time, the custom was to pay 5% on the first $100,000 and 2% on the balance if the listing was exclusive and 7%/2% on an MLS listing.
I do not know if it's true, but once upon a time it was rumoured that in Ontario (or at least Toronto) realtors charged 5 to 7% on the full gross amount! So a million-dollar sale meant a commission in the order of $50,000 to $70,000. Nuts.