add_filter( 'woocommerce_cart_shipping_method_full_label', 'add_0_to_shipping_label', 10, 2 );
function add_0_to_shipping_label( $label, $method ) {
// if shipping rate is 0, concatenate ": $0.00" to the label
if ( ! ( $method->cost > 0 ) ) {
$label .= ': ' . wc_price(0);
}
// return original or edited shipping label
return $label;
}