There's a few ways to add a markup to your pricing in Powered Now. You can also hide it from the customer if needed.
The first option is in the product catalogue - Please see, How to set up your product catalogue?
The second option is to add it during the creation stage.
Once you enter your item descriptions you will see the discount and markup box.
You can add the markup as a percentage or a fixed amount.
To hide the markup - Please see pricing layout (Document and Logo Settings)