[jQuery] Toggle - change clickSymbol

[jQuery] Toggle - change clickSymbol


Hello,
im using the script from this site here http://host.sonspring.com/portlets/
But now i need a solution to change the clicksymbol (- if the content
is open and +.jpg if the content is closed/toggle).
in my HTML im only using this here:
<div class="portlet_topper" style="position:relative;">
<a href="#" class="toggle" style="margin-
left: 10px;">
<img src="mini.gif" alt="Mini"
border="0">
</a>...............
the Script is:
$(document).ready(
    function()
    {
        // Toggle Single Portlet
        $('a.toggle').click(function()
            {
                $(this).parent('div').next('div').toggle();
                return false;
            }
        );
    }
);
Did someone knows the way to change the JPG there?