WooCommerce Hooks

Cart

add_action('woocommerce_cart_calculate_fees', function($cart) {
  if (is_admin() && !defined('DOING_AJAX')) return;

  $percentage = 0.02; // 2%
  $percentage_fee = ($cart->cart_contents_total + $cart->shipping_total) * $percentage;
  $cart->add_fee('Service Fee: ', $percentage_fee, true);
}, 10, 1);