Kwesty Yon

I posed this question in the comments at Ricki's but I'm going to go ahead and pose it here as well:

Let's say you are doing quick shopping and you want to use the express lane. Does the 20 items or less mean:

1. 20 individual items, or
2. 20 different kinds of items?

That is, say I have 15 different kinds of things and also have 10 boxes of Kraft Mac-n-Cheese. Does that mean I have 25 items or do I have 16 since the cashier (at some places) can ring up multiples as one item?

I know where I stand on this, I'm interested to know where other people stand.