Ivan Popov

This plugin lets you attach an extra fee — either a percentage of the cart subtotal or a fixed amount — to any WooCommerce payment gateway or shipping method. Configuration lives under WooCommerce → Settings → Checkout Fee.
Typical use cases:
<ul>
<li>Pass card-processing surcharges to customers paying with specific gateways.</li>
<li>Add a handling fee for Cash on Delivery.</li>
<li>Add a packaging/insurance fee for express shipping methods.</li>
</ul>
Features:
<ul>
<li>Per-method configuration — every payment gateway and shipping method has its own settings.</li>
<li>Choose between a percentage of cart subtotal or a fixed amount.</li>
<li>Optional taxable flag so the fee can be included in tax calculations when required.</li>
<li>Customisable fee label shown to the customer.</li>
<li>Works with the classic checkout and the block-based Cart & Checkout.</li>
<li>Declares compatibility with WooCommerce High-Performance Order Storage (HPOS).</li>
</ul>

Payment and Shipping Method Checkout Fee for WooCommerce

Add a percentage or fixed fee to any WooCommerce payment method and shipping method at checkout.

aversus

Adding Extra Tax or Amount is a lightweight WooCommerce extension that provides a customizable checkbox on the checkout page. When checked, it adds a pre-defined tax or extra fee to the order total instantly via AJAX.
Key Features: 
* Checkout Integration: Now focused exclusively on the checkout page for a better user experience and to prevent duplicate fees. 
* Fully Customizable: Change colors, text, and hover effects from the admin panel. 
* Calculation Types: Choose between a percentage (%) of the subtotal or a fixed amount. 
* Real-time Updates: Uses WooCommerce’s <code>update_checkout</code> AJAX trigger to update totals without page refresh. 
* Open Sans Font: Clean and modern typography. 
* Enable/Disable: Easily toggle the plugin from the settings page.
Developed by Mehmet Balcı.

Adding Extra Tax or Amount

Allows customers to add an optional tax or fee on the checkout page with real-time AJAX updates.

Payment and Shipping Method Checkout Fee for WooCommerce vs Adding Extra Tax or Amount