{$ cart.totals.total.amount + $ cart.subtotals.tax.amount | string_format: "%. 2f"} {$ currency.sign}
replace for
{$cart.totals.total_including_tax.value}
the full div would be
<div class = "cart-summary-line cart-total">
<span class = "label"> {$ cart.totals.total_including_tax.label} </span>
<span class = "value"> {$ cart.totals.total_including_tax.value} </span>
</div>