Easy solution is to have a 2 tier wallet.

one is your everyday wallet - use it to accept payments you can see are confirmed by the time the pizza is ready - and at various points throughout the day you transfer portions (or all) to your second wallet stored on a usb stick in a bank deposit box or safe.

No block explorer necessary

if someone steals your wallet dat, they can only ever steal a day's takings (or however high you let it go). If money goes missing, you delete your wallet dat, clean /format and better secure your pc, and get a new wallet dat.

The only way an employee can steal bitcoins is by either transferring to a strange key, or stealing wallet dat file (so you'll lose as much as you allow in that account at any one time). If you basically transfer to safe wallet as soon as payment is "confirmed", there shouldn't be much loss at all.