Yeah...the challenge is that if you give the cashier money after they've punched in the amount they get flustered. I agree...making change should be a skill one should be able to do without a cash register. When I was young I helped my mother at lots of craft shows. That's how I learned to make change!
I was in the library once with my son (a homeschool kid) and he was working on copy work for cursive writing. One of the other patrons actually came up to me and thanked me for teaching him how to read cursive. She evidently had given someone a letter written (or note) written in cursive and that person couldn't read it.
Even though we have a 'technical' age, I still think some basic skills are important.