add_action( 'woocommerce_before_calculate_totals', [ $this, 'calculate_price' ], 10, 3 );
add_filter( 'booking_form_calculated_booking_cost', [ $this, 'set_booking_price' ], 10, 3 );

public function calculate_price( $cart ) {
    if (!is_user_logged_in())
        return;

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 )
        return;

    $user = wp_get_current_user();

    if( in_array('trusted_customer', (array)$user->roles ) ) {
        foreach ( $cart->get_cart() as $cart_item )
        {
            if( isset($cart_item['booking']) ) {
                $cart_item['data']->set_price(0);
            }
        }
    }
}

public function set_booking_price( $booking_cost, $booking, $posted )
{
    if (!is_user_logged_in()) return;

    $user = wp_get_current_user();

    if( in_array('trusted_customer', (array)$user->roles ) ) {
        $booking_cost = 0;
    }

    return $booking_cost;
}