Hi,

Try the code like below.

in .py

class AccountInvoiceReport(models.Model):
    _inherit = 'account.invoice.report'
    
    total_w_tax = fields.Float('Total With Tax', store=True)
    
    def _select(self):
        res = super(AccountInvoiceReport, self)._select()
        select_str = res + """, move.amount_total AS total_w_tax """
        return select_str

https://ibb.co/7jRh0Wf

https://ibb.co/ypxm4kV

Regards

Good morning, 

If field total with tax not exist,

Add function calculate TotalWithTAX and affect it to new field,

then you can inherit view graph of invoices then add your field with 

type="measure"