You can edit your nightly rates in your PMS at any time without affecting the website booking engine.
How rates reach your website. HomeRunner reads nightly rates directly from your PMS calendar. A rate change you make in Guesty, or any other connected PMS, appears on your website on the next calendar sync, the same way any other rate change does. You do not need to change anything on the website or in the HomeRunner plugin.
Existing reservations keep the price they were booked at. The booking engine displays the exact nightly rate from your PMS, cents included.