If you are GST Registered, or if you are operating under your own TSL; you should be getting the full GST inclusive portion of the rental fee (less Mighway commission) plus the full GST inclusive portion of any additional fees. You are obliged to remit GST to the Inland Revenue Department through your GST return (if applicable). For example, if you are a local owner with a combined daily rental rate of $1000 and a $100 cleaning fee, you will receive $850 for the rental and $100 for the cleaning fee. If you are not GST registered, you will get those amounts less 15% GST, unless you are using your own TSL.
Read more about TSLs here: https://www.mighway.com/nz/en/owners/gst-tsl