I carry cash, DH carries cash, and our kids carry cash. But in very small amounts. We like to have it on hand for places where we will make small purchases or where you cannot use a credit or debit card, which for us is a lot of places......most vendors at local Farmers' markets, Flea Markets, garage/yard sales, church or community festivals, etc. only take cash.
Plus, even if a local business allows credit/debit card use for purchases under $10, we feel bad to do that knowing they're going to take a processing hit for it. So we try to pay cash in those places, too.
We also tend to use cash on the road for vending machines, turnpike plaza food court purchases, drive-through food or drink stops, etc. And for tipping purposes when eating out or traveling.