## Function Description
The `cancelOrder` function is responsible for cancelling an order by sending a POST request to the appropriate API endpoint. It constructs the request with necessary parameters such as the order ID, and sends it using the method. If the response from the API indicates success, it returns `true`.
## Example Input
``` php
$orderId = 'IZ07BFA2EE08';
```
## Example Output
``` php
true
```
