It's really a win-win for everyone. Train your employees on what products have the highest margins and after 3 months of employment you share x% of all profits during their shift in their next paycheck. Even something like 2% would motivate me a hell of a lot more to sell the dumb shit owners want me to sell. Overall sales would go up and your employees would take an active interest in trying to make your business more profitable. I don't understand why this isn't common practice.
When I worked at game stop as a kid, we always were told to push warranties (the highest profit margin statistically) and were tracked and ranked on who sold the most. I never gave a shit because I could sell 100 warranties in a shift and not see an extra penny in my paycheck.