One of the the first questions to customers asking for a refund would be if they would like to have a credit under their name to use for future use. This way the money stays within the company. Here is how this can be done:
Open up the Invoice that you need to reverse.
Press Checkout button once you have reversed all the necessary items.
Make sure you have the correct person showing as "Invoiced"
Change the payment type to "Account Credit". What this does is create a credit of the amount in the shopping cart towards the person who is being invoiced. NOTE: Not all employees will be able to see the "Payment Amount" box at the bottom of the page. You must have Customer Credit authority in Employee Authorizations.
Choose whether or not you want to e-mail the receipt to the customer. Check the box if you do not want to send them a receipt.
Write a payment note under the Add Note section, saying what happened and why you are giving them this credit.
Hit "Apply as account credit" button.
Go to the customer's profile page to make sure you see that they have a credit to use for future use.