For CartIt Unix 4.0, 5.0, and 8.0 -
Replace the following:
<A HREF="%io_home_page%">Continue Shopping</A>

with this:

<a href="javascript:history.go(-1)" onMouseOver="self.status='Click this link to Return to Previous Page.';  return true" onMouseOut="self.status=''; return true">Continue Shopping</a>