Adding a handling fee for shipping if order total is too low

I want to add a handling fee for shipping if order total is too low. How can I accomplish this?
Is there a single extension to do this or do I have to use multiple extensions?

I can't add the fee in Order Totals because I don't want customers who pick up their products from the store to pay extra shipping fees.
We are currently using OpenCart version 2.0.3.1

For example:
---------------------------------------------------
Order Total - Shipping - Handling fee
32€ yes 0€
8€ yes 4€
8€ no 0€
---------------------------------------------------

If you want a total-based fee that is also based on the shipping option selected by the customer, you can use Shipping-Based Fee/Discount. You'd set it up like this:

------------------------------------------------------------------------------
CHARGE #1
Title: Handling Fee
Group: A
Charge Type: Total
Charge Field: 0-7.99 = 4.00, 8.00-31.99 = 0.00
Rule: Shipping Method is not Collect From Store
------------------------------------------------------------------------------

Note that a $0.00 fee won't show up as a line item, so you wouldn't need the 8.00-31.99 bracket unless you actually have a fee there. I wasn't sure if that 0.00 cost was a mistake, so I left it in to show the bracket syntax.

Feel free to take a look at the screenshots and demo site, and if you're interested let me know at www.getclearthinking.com/contact if you have any further questions.