Do you have a credit card?
Yes, several. Primaries include a Visa, a Discover, and an AmEx Blue (6% on groceries, 3% on gas).
How do you use it on a monthly basis?
I carry it around in my money clip and take it out to buy things. :p
Generally, my wife & I use whatever card is giving us the highest rewards on what we're buying. Or, failing that, whichever one is supported.
I get on DH's case about paying cash on bigger purchases when we could be earning credit card rewards. They add up to several hundred dollars' worth every year.
Is he getting cash discounts? If I'm paying for something large, I always ask if there's a cash/check discount, and if so, I pay it that way. CC fees are normally 3%, and I generally don't get that high of rewards for medical payments/dental work/etc, so I'll take the cash discount if it's better than what I can do with a CC.
A credit card is simply an unnecessary layer of expense for companies that artificially drives up the price of goods. You're only perceiving to make money, though it's certainly money you'd otherwise be leaving on the table. So in reality, you're not making anything, you're paying for the convenience of the card and only getting back the money you were "owed" in the first place.
Only true if you can negotiate a cash discount. You're not going to negotiate a few percent off at a grocery store typically, so may as well use a rewards card.