tax calculation in total amount

Tax calculations are enabled on my woocommerce store.

How i am using your plugin?
I am using it to provide discount on several payment gateways.

What is happening?
Woocommerce tax calculations are applied on that 50 amount which is added by your plugin and it is changing that 50 to 52.50 (5% tax which i setup in tax settings)
screenshot- https://nimb.ws/06zwfp

I don’t want the woocommerce tax to be applied on your plugin field value.

Please provide the solution.