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