Hello,
i didn't find configuration to change the price in the dashboard orders, but i think you can do it manually:
change line 131 in dashproducts module class (dashproducts.php)
'value' => Tools::displayPrice((float)$order['total_paid_tax_excl'], $currency),
to
'value' => Tools::displayPrice((float)$order['total_paid_tax_incl'], $currency),
and also the labels (line 106, same file)
array('title' => $this->trans('Total', array(), 'Admin.Global').' '.$this->trans('Tax excl.', array(), 'Admin.Global'), 'class' => 'text-center'),
to
array('title' => $this->trans('Total', array(), 'Admin.Global').' '.$this->trans('Tax incl.', array(), 'Admin.Global'), 'class' => 'text-center'),
p.s: version 1.7