When you select Print, this is the dialog you get.
The output will not adhere to your CSS so don't expect it to be pretty. There's information about this on my site.
It might be better to create PDFs and make them available from the TOC or somewhere in your help.
See www.grainge.org for RoboHelp and Authoring tips
I'm referring to a WebHelp project. I should have been more specific. Is there a way to print all topics in a book from the table of contents?