Admin → Extensions → Order Totals
Charge an extra fee to the customer during checkout. Handling charges are typically used by merchants as a way of recouping order payment costs.
Status: MUST be "ON" for the order total extension is displayed when checking out.
Order Total: Minimum order amount to be reached to apply the fee. If customer order total will exceed this amount, handling fee will not be applied. This is main value but overridden with payment specific settings.
Fee: Free to be added to order total if minimum amount condition is not met. This amount is overridden by payment specific setting.
Payments: Select a specific payment you need to add the fee to. These settings will override the main settings if selected payment is used by the customer.
Payment's config Order Sub-Total: Minimum order sub-total amount to be reached to apply the fee. This overrides main Order Total setting.
Tax Class: Select Tax Class if you need a tax to be applied on top of the fee.
Type: select type of fee (for internal purposes).
Sort Order: Sort Order set's the order of which the Order Total extension will be displayed amongst others.
Calculation Order: Set's the order of which the Order Total extension will be calculated amongst others.
Each order total have own internal logics to all calculations. Even if you change calculation order it is based on order total's logic to ignore or use calculation order.