need guidance on encode JSON and sorting

in the script this is all i am using JSON as:

....
use JSON::XS;
....
.....
$return_json_text = encode_json $tmp_hash;

this variable ($return_json_text) is then used to display values. I need this to be orderd, but not able to figure how to order the outcome??? I read about $enabled = $json->get_canonical on JSON's page but not sure hot use it as i do not have $json or such object created. Also I am assuming it would be sorted on key field of the JSON hash.

ty.
Rajeev
.