Open this INI file:
/components/com_virtuemart/language/en-GB/en-GB.com_virtuemart.ini
and look for this line:
COM_VIRTUEMART_CART_TOTALP="Total <strong>%s</strong>"
Translate it the way you want.
BUT -- Make sure not to touch the
%s, because it will be replaced with the amount in the website.
regards.