This doesn't apply to those looking for comps, but...

Go to caesars.com.

Go through the normal booking process.

When you get to the point where it's asking you to pay, close the window.

Wait a few hours.

For many dates/properties, it will email you an offer to get 5% off if you complete your booking.

It's a marketing trick to try to push the customer into completing a booking where he almost got to the end.