No need to muck about with limits based on serving size. Just mandate a consistent portion size for labeling and allow manufacturers to also label with an additional serving size of their choosing. So everything, tic-tacs included, would be labeled with nutrition facts for say 3 oz (or even a flat 100g to be consistent with EU), and then tic-tacs could also include labeling for per piece.

Yes, the games played with serving sizes can be ridiculous.

But, at least in this case, if sugars are present in a food, but at less than half a gram per serving, the label can claim the food to be sugar free, but does still have to contain a disclaimer saying that sugar is present.

Welcome to bureaucracy.

But why? This is like worrying about pennies on a thousand dollar price.

A tic-tac is zero sugar in the context of a person's normal daily intake.

Except for those who took (and paid attention in) a chemistry class, most people are woefully ignorant of precision and significant figures.