Point of Sale database - does it exist?

I need to (very quickly) create a program that is user friendly that would be
used by a small corner store to track sales/inventory/expenses/employees/etc.
the main issue is it need to track every sale by the employee entering (by
combo boxes) categories then choosing the product and then that would bring
up the price and a quanity box. The employee would enter all the products
for each sale and would get a running total for each client. Once the sale
is complete it would update the inventory to subtract the quantities sold.
Other ideas is to be able to have promotion prices for regular clients,
pop-ups to show when inventory needs to be restocked and so on. I know
there are inventory databases out there but I can't find one to for a point
of sales program. Does anyone know if it exists? Is there a template out
there somewhere. I started trying to create it myself but as it turns out,
spending the last 3 years with a baby did nothing good for my brain and
programming skills. I have very little time and fear I may need to accept
defeat! PLEASE HELP!!!!!