This is a real pain point for people in hospitality and similar industries, both for business operators, and employees. Software can solve the problem elegantly.
But OP's venture was likely too late to the party.
Deputy claimed 100K+ users in 2015 (2 years before this thread started). Their pricing is $2.50 per user. I'm sure there are other similar companies.
Would be interesting to hear an update on how this panned out for OP though.