"make it sure that it works on ie6" is the worst line you can hear at work. especially if you're developing a web app. even global websites like fb don't support ie6 anymore. http://www.w3schools.com/browsers/browsers_explorer.asp - IE6 has 2.6%, I don't really see a point in spending hours optimizing stuff for it.
On the flip side, if you're short on resources and that time would be better spent adding functionality which would result in > 2.6% return, then by all means ignore IE6.