Is there a way to add taxes and fees so that it carries over into the invoicing section?

It is an invoice line item as any separate charge. However, if you are referring to surplus lines tax that the AGENCY is responsible for collecting, filing and paying, you can set it up as a government tax in configuration, which is usually a percentage of the premiums and fees and then you assign the tax to the premiums and fees.

You can't set a standard fee/ tax that will always carry over into an invoice if that is what you are looking for. In our system we have CTAX - Company Tax and CFEE - Company Fee that are transaction codes that we add to the transaction for those items.

Taxes and fees are processed as transactions to a policy. You can add custom transactions in Configure>Accounting>Transaction Codes.