[Feature Request] Add GST for Tax Identifiers

[Thor]

Seeing as GST is a tax identifier used in the following countries:

• Australia
• Canada
• India
• Malaysia
• Maldives
• New Zealand
• Papua New Guinea
• Singapore

It should be a tax identifier we can use and it's not currently an option. This is a deal-breaker for myself and many using ShipStation.

[Skybox]

This is what we are currently dealing with. Love all the options Shipstation offers, but our accounting team is having difficulty reporting the GST on shipments.