To start, go to Inventory > Bundles:
Click New Inventory Bundle:
Here, you can name your bundle, add items from your inventory, optimize the price by line item, or make an overall price for the bundle:
The items included here will be driven off your inventory so it's also possible to include a mix of taxable and non-taxable items. The system will handle calculating things properly for the bundle. You can also create a UPC code for the combined bundle.
To add a bundle to an invoice, simple select if from the list in the Bundles section:
You can then click the expand button on the invoice to see what's included but only the single item will be visible on the invoice for customers:
Also, to make creating many bundles quick and easy (for instance, for screen replacements for many different models of phones), you can use the Clone button when creating bundles in Inventory > Bundles: