Most people don't consider taxes “fun” but I'd like to help you at least not think of them as “hard.” The first step is helping you to organize your sales information so that you have the information you need when you need it.
The easiest way to do that is to create an Excel file. Find out the first month of the sales tax year for where you live and type the twelve months of the year in the columns across the top. Then list all the cities where you sold physical copies of books or other physical products in the rows on the left.
Now you only need to fill in how much you earned each month in each city. (See my example below.) I usually add a “comment” to each cell with additional information on each event, how many copies were sold, and any other helpful information like what “Receipt” this information is linked to in QuickBooks.
Double-check the tax rate for each city – taxes do go up! – and calculate the total tax you expect to pay. (Remember, this is money you already collected from your customer at the sale.) If you keep this information up-to-date each month, at the end of your tax year you'll have all the information you need to fill out your tax form!