DocTract is highly rated by Capterra as a source for policy and procedure writing software. I haven’t used them myself, but you could take a look there. If you’re talking about something like a nonprofit shop, you could talk to some of your retail neighbors and ask them to share their internal policies with you, as a place to start. If it is a shop, I would start with a requirement that two staff/volunteers (unrelated, not of the same household) be present at all times and then head right into a cash-handling policy first. From there you can develop inventory processing policies: receiving/unpacking inventory, periodic counts, pricing, etc. You will also want to have policies regarding staff/volunteer purchases: does the inventory have to be available for sale for a certain period before it can be purchased by staff/volunteers, staff/volunteers cannot ring up their own sales, etc. It’s easiest to think of a day-in-the-life of your venture and the individual types of policies — and procedures — that will be necessary, than to tackle it all as one big policy.