Where is the Walmart you go to? Here in Washington state you buy your ammo at the gun counter and just carry it around if you need to do more shopping. The only case of having your purchase carried by staff to the front counter is a Cabela’s and that’s if you’ve bought a firearm. I’ve not bought a firearm at Wally’s so I’ll find out this time how that works.
Our Walmart has the same policy. The employee has to carry it up to a register where you can get it when you check out.
Our Walmart also stopped selling guns a number of years ago.