Tax included on the total of the product in the sales invoice

I am configuring an instance of ERPNext and for the client’s country it is asked that the tax is included on the total of the product at the time of making a sales invoice, what I want to achieve is that when the product is selected in the invoice it already has including tax on the total.

How have you configured the taxes so far or attempted to do so?

You can look at configuring the taxes and charges template for achieving this. Once you’ve added the tax %, you can check the option Tax Included in Basic Rate. This will reverse calculate the tax and adjust the same in the product’s price:

https://docs.erpnext.com/docs/user/manual/en/selling/sales-taxes-and-charges-template#21-sales-taxes-and-charges-table