Do you trust your employees? If so, you're ahead of the game. But, once you trust your employees, are you happy with their productivity?
My guess would be that you're not. It's not necessarily because they are incompetent, or that you didn't show them how to do the job, but it's probably tied to the latter. If you have employees that you trust, but are underperforming, they may be lacking the tools to be more productive.
It's hard to tear yourself away from the immediate tasks at hand to train employees to do the things that you can do yourself, but just think what you COULD be doing if your employees (even just a manager or assistant manager) were handling all of the mundane chores that you find yourself doing.
Spend a little extra time each week with your best couple of employees, including showing them how to use the point of sale system to do things like inventory counts, ordering and receiving, and system maintenance, and they can take a big workload off your shoulders.
There will always be bad employees, or employees you don't necessarily trust with an open cash drawer, but identifying a few key employees, and then empowering them with training and access to the important information in your store will result in more time for you to spend growing your business, instead of just maintaining it.