the $5 fee will only be applied if any of the three items is in the cart?
In this case, you will need to know the ID of the 3 items
Set up the charge rule with the trigger:
Presence of Item In cart
If Item '<id for item1>' 'exists' in the cart
OR
Presence of Item In cart
If Item '<id for item2>' 'exists' in the cart
OR
Presence of Item In cart
If Item '<id for item3>' 'exists' in the cart
then set the calculation to a flat rate of $5