This filter is applied for the get cart data . The returned data can be modified through this filter.
The sample below shows an example of how you could modify it:
function rpress_cart_data_callback' ( $return ) {
$return = array(
'fee' => $fee,
);
return $return ;
}
add_filter( ' rpress_cart_data', 'rpress_cart_data_callback', 10, 1 );