When you multiply the per-night rate by the number of nights, the result can differ from the displayed total by a cent or two. The displayed total is the correct amount and is what your guest is charged.
Why this happens. The per-night figure is a calculated average: the full stay total divided by the number of nights. When the stay total does not divide evenly across the nights, the per-night number is rounded to the nearest cent for display. Multiplying that rounded number back out by the night count then differs from the true total by a cent or two. This is standard for any averaged nightly display and matches how Airbnb, VRBO, and Booking.com present the same math.
What you can do. If the rounding causes confusion for your guests, the per-night label can be changed to something like "avg / night" to make clear it is a calculated average rather than a fixed nightly rate.