Most business will often have some customers that have different requirements when dealing with them.
It would be very helpful to have the ability to add a pop up alert when entering a sale to remind people of any special instructions required for specific customers.
eg: If a customer attracts special pricing for a limited number of products
The ability to have different price categories allows for 6 different options but this is only helpful for a limited number of customers and only for pricing situations.
Pop ups could be used to remind that a customer needs a certificate of compliance or a booking number etc.
I believe this could be useful for many things.