it looks like you are using a 2columns-right template in your cart, try this one :

app/design/frontend/{package}{theme}/layout/local.xml

<checkout_cart_index>
    <action method="setTemplate"><template>page/1column.phtml</template></action>
<checkout_cart_index>

it looks like you are using a 2columns-right template in your cart, try this one :

app/design/frontend/{package}{theme}/layout/local.xml

<checkout_cart_index>
    <action method="setTemplate"><template>page/1column.phtml</template></action>
<checkout_cart_index>

If it doesn't work try this:

Go to : app/design/frontend/{package}{theme}/template/checkout/cart.phtml then move <?php echo $this->getChildHtml('totals'); ?> to :

...
    </tbody>
</table>
/*Here*/
<div class="row">
    <div class="col-md-6">
        <?php echo $this->getChildHtml('totals'); ?>
    </div>
</div>