i've never been carded at the CVS i go to... and idk about kroger... dont think we have one here...but if they have a self checkout you should be able to purchase it w/o trouble...
What i do is i go to shoppers, and i dont buy at the pharmacy section but right at the pharmacy section, down one isle they sell robotussin and everything, so i just bring however many i need to buy to the front, the people at the front checkout usually dont know shit about any dxm
at walmart i found that some cashiers card, and some dont, they just give you a glance up and down, say how old are you, you say 18, they sell it to you, heck some dont ask any questions. and its weird, all the dxm containing products are right there in the isle except coricidin, you have to take a card up to the pharmacist to get it. but at the 99cent store in my town they never card or ask my age.
Haven't tried buying any lately, but I'm sure they would card here. Clovis is the most stuck up, goody-goody town I have been to.