Woocommerce subscription custom fee add to recurring total - php

Question

I would like to ask how to add a custom fee to the woocommerce subscription recurring total?
Found this on the web:
function woo_add_cart_fee() {
global $woocommerce;
$woocommerce->cart->add_fee( __('Custom', 'woocommerce'), 5 );
}
add_action( 'woocommerce_cart_calculate_fees', 'woo_add_cart_fee' );
However that certain function is just for the regular product. NOT SUBSCRIPTION — it doesn't add the fee to the recurring totals.

Answer 1

As of right now, WooCommerce subscriptions doesn't support adding fees to recurring totals.

Answer 2

This may be too late to be of any use to you, but you might find this useful: https://docs.woocommerce.com/document/subscriptions/develop/recurring-cart-fees/
I believe this example would be relevant to your question:
In some cases, you may require the fee to only apply to the on-going
recurring payment for any subscriptions. To achieve this, you need to ... add a condition to check whether
the cart being passed into your callback is a recurring cart, or the
standard WooCommerce cart.
Recurring carts have a $recurring_cart_key property we can use to
determine if the cart is a recurring cart.
add_filter( 'woocommerce_cart_calculate_fees', 'add_recurring_postage_fees', 10, 1 );
function add_recurring_postage_fees( $cart ) {
// Check to see if the recurring_cart_key is set
if ( ! empty( $cart->recurring_cart_key ) ) {
$cart->add_fee( 'Postage', 5 );
}
}

Answer 3

If someone comes by this question, you can solve it in the following way:
add_filter( 'woocommerce_subscriptions_is_recurring_fee', '__return_true' );
add_filter( 'woocommerce_cart_calculate_fees', 'add_fees', 10 );
function add_fees($cart) {
$total_fee = $cart->get_subtotal();
WC()->cart->add_fee( 'Fee', $total_fee * 0.2 );
}
or
add_filter( 'woocommerce_subscriptions_is_recurring_fee', '__return_true' );
add_filter( 'woocommerce_cart_calculate_fees', 'add_fees', 10 );
function add_fees($cart) {
WC()->cart->add_fee( 'Fee', '10' );
}