Formulas used:

total = (inter price + expenses + manual_expense ) – early bird + city fee+ cleaning fee + sec deposit

$early_bird_discount – doesn’t include extra guest, security, city fee, cleaning fee

$you_earn = $total_price – $security_deposit – floatval($city_fee) – floatval($cleaning_fee) – $service_fee;

$taxes = round ( $you_earn * $taxes_value/100,2);

$price_for_service_fee = $total_price – $security_deposit – floatval($city_fee) – floatval($cleaning_fee);

city fee % Doesn’t consider price for extra guest

city fee % Doesn’t consider extra expenses (added when owner issues invoice)

100% deposit includes automatically expenses (city fee / cleaning fee) – even if the option is set to NO

How to add a new item in booking formulas

There are many places where you need to do the changes and for that reason it’s difficult to give step by step instructions.
Start on wprentals-core plugin – file post-types/invoices.php – you have there function wpestate_super_invoice_details and wpestate_invoice_details functions that are used to create and display invoices.
Also a very important function is wpestate_booking_price in wprentals theme folder – file libs/help_functions.php
In this function we do all the math. So you can start by looking into this.