i dont think you need to mess with background position for this one
.pal-rating-static {
background: url("../images/icons/pal-rating5.png") 0 0 no-repeat;
width: 102px;
height: 27px;
display: block;
}
if this is your bar with 5 'skulls' visible . then all that you need to do is make the container smaller when you want to display less 'skulls'
you can do this by adding an extra CSS class for numer of 'skulls'
so you will end up with something like this
.pal-rating-static.cat1 {
width: 20px;
}
.pal-rating-static.cat2 {
width: 40px;
}
.pal-rating-static.cat3 {
width: 60px;
}
.pal-rating-static.cat4 {
width: 80px;
}
hopefully this will solve your problem .. a fiddle would be very useful