One of my first college jobs back in the days was at RadioShack. I hated a) asking everyone for their address, regardless of how small the purchase, and b) having to ask them to buy a $19.95 extended warranty on a $5.95 pair of headphones. Our district manager used to give salespeople an extra $5 out of his pocket for anyone who could sell a warranty that cost more than the purchase cost of the product. I never sold one.
Probably because I wasn't so pushy, I used to get a fair number of customers, but we were a pretty low volume store in a sleepy suburb my numbers were average.