Just a quick note that it appears that some of the tablet or mobile point of sale systems are no longer working in retail stores that sell tobacco related products like cigars, e-cigs, vaping products and cigarettes. This is likely due to the high risk nature of these businesses which limits the number of companies that provide merchant services to retail stores that sell tobacco related products.
There have some been stores reporting to me that there systems just stopped working and they quickly had to find a new point of sale system.
Only advice that I can offer is to be sure that both your point of sale system and whoever is handling your merchant services understands that your business sells tobacco products and will continue to support and service your type of business.
If you want to see the discussion which does mention point of sale solutions by name, you can visit this forum discussion (warning - R rated language):
Are you in the US and in need of no cost retail point of sale advice? I'm happy to help and can be reached on my cell at 208-340-5632 (I am on Mountain Time) or via email at firstname.lastname@example.org. There is also a contact form to the right that can be used to reach me.