Cart Item Sub Total

add_action('woocommerce_cart_calculate_fees', 'add_handling_fee_on_payment_gateway_selection');
function add_handling_fee_on_payment_gateway_selection() {

    // Check if this function is being called in an admin page or an AJAX call, if yes, return
    if (is_admin() && !defined('DOING_AJAX')) {
        return;
    }

    // Check if a payment method has been selected, if not, return
    $payment_method = WC()->session->get('chosen_payment_method');
    if ( empty( $payment_method ) ) {
        return;
    }

    // Define the handling fees for different payment methods
    $flatFee = 1; // Payment Gateway Flat 1 Fee
    $stripePercentFee = 0.029; // Stripe Payment Gateway 2.9% Fee
    $tabbyPercentFee = 0.065; // Tabby Payment Gateway 6.5% Fee

    // Check the payment gateway ID and calculate the handling fee accordingly
    if ( $payment_method === 'stripe' ) {
        // Calculate the discounted subtotal of the cart with shipping
        $DiscountSubTotal = (WC()->cart->get_cart_contents_total() + WC()->cart->get_shipping_total());
        $totalFee = ($DiscountSubTotal * $stripePercentFee) + $flatFee;
    } elseif ( $payment_method === 'tabby_installments' ) {
		
    // Set the regular price as the product price
    $regular_prices_total = 0;
    foreach (WC()->cart->get_cart() as $cart_item_key => $cart_item) {
        $product = $cart_item['data'];
        $regular_price = (float) $product->get_regular_price();
        $cart_item['data']->set_price($regular_price);
        $regular_prices_total += ($regular_price * $cart_item['quantity']);
    }
		
    // Update cart item subtotal to regular prices total
    WC()->cart->set_cart_contents_total($regular_prices_total);

    // Calculate the regular subtotal of the cart with shipping
    $regular_prices_total += WC()->cart->get_shipping_total();

    // Disable coupons
    WC()->cart->remove_coupons();

    // Set a standard shipping rate
    WC()->session->set('chosen_shipping_methods', array('flat_rate:1'));
    WC()->shipping->calculate_shipping(WC()->cart->get_shipping_packages());

    // Calculate the handling fee
    $totalFee = ($regular_prices_total * $tabbyPercentFee) + $flatFee;
}  else {
        $totalFee = 0; // No handling fee for other payment methods
    }

    // Add the handling fee to the cart
    WC()->cart->add_fee(__('Handling Fee', 'txtdomain'), $totalFee);
}

I added this code to assign some extra fee depends on the payment gateway selected. everything is working well so far but I’m facing an issue with WC()->cart->set_cart_contents_total($regular_prices_total); I want to display the items sub total regular prices not the discounted price for particular gateway. $regular_prices_total this variable I want to show to the customer as sub total of the items when that particular payment gateway is selected. I passes the variable to the setting subtotal amount function but I don’t know why it is now showing there at the checkout page.

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