Country Currency Checkout

We have two pricing zones
AUD with Standard tax Rates 10% GST
NZD with Standard tax Rates 15% GST
We only sell to these countries and pricing changes based on IP address in the store.
At check out the currency is displayed in the correct currency.

WooCommerce > Settings > Zone Pricing > Pricing zones > New Zealand
Currency New Zealand dollar ($)

Exchange Rate 1 AUD = [ ]

Why do I need to add an exchange rate since we have already manually added the AUD and NZD prices to the products. No exchange rate is required.

NZ products are purchased in NZD
AU products are purchased in AUD
But when I zero out the Exchange rate I get the following error.

“Exchange rate must be nonzero.”

I want to have the check out process and payment gateway process the payment in the currency of the country.

https://www.pricebasedcountry.com/docs/faqs/does-the-plugin-allow-set-the-base-currency-for-the-checkout-process/

https://www.pricebasedcountry.com/docs/faqs/will-it-compatible-with-my-payment-gateway/

We are using PayPals Braintree Payment Gateway and we have setup

https://docs.woocommerce.com/document/woocommerce-gateway-paypal-powered-by-braintree/#multicurrency-setup

AND

https://developer.paypal.com/braintree/articles/control-panel/important-gateway-credentials

If the gateway processes in the currency in the checkout – then why do we need to have a value in the NZD Exchange Rate field.

Exchange Rate 1 AUD = [ ]

If it can’t be zero then what should it be so that the NZD is not converted on passing the value to the Payment gateway.