The appointment types that you would've added in your account settings have an associated cost for the client. However, if you'd like to give your client a discount so that the correct reporting appears on your dashboard and also appear on their invoice, you can do so!

Either click on the appointment and choose Invoice details, change the price. Or after you've created an invoice, click on the menu item to edit it, change the amount under Appointment price. This will reflect on the total amount due to your client.