10 Brain Cells or fewer

It is an interesting debate. Does the sign "10 items or less" at the checkout counter at the grocery store violate the laws of grammar?

The argument is that the word 'fewer' should be used when it refers to quantities that can be counted. 'Less', they say, should refer to quantities that cannot be counted.

All I know is when I have 2 shopping carts full of individual items, they cannot be counted so I can clearly use the 10 items or less line but not the 10 items are fewer. SO I don't know why the people behind me were complaining...they only had 1 or 2 items each, it wouldn't take them long to get through when I was done...