Is there a report of how much shipping I charged on each order?

Yes. Go to Analytics → Reports and open Shipping by order (in the Finances category, or type it in Search reports…).

It lists Shipping charges and Total shipping charges for each order, counted once per order. You can change the breakdown to Day, Month, Country, Region, City or Sales channel, and pick the date range at the top.

Use it to compare what customers paid for delivery against your courier invoices. You can export the table as a CSV file to work on it in a spreadsheet.