If a standard fee applies on a specific Booking type, you can add it as a Pre-Defined Service to the Booking itself.
Go to Toolbox > Settings > Booking Defaults > Name / Customs > Server Setup > Modify > and enable the Ad-Hoc Extras option.
When making a new booking with the associated Booking Name, a window will appear for adding Services.
Web Users will be able to view these services in the Time Report window > Extras tab.