printer software for some special purposes..

i have a 9 pin dot matrix epson lx-300+ printer, and i will be using it in my departmental store i want a software in which i will just have to put the price numbers and when i press enter or else this software sum all the prices and then send that to the printer, and printer will out put that on a slip.. we don't have to mention that what is being purchased, mean just have to print the prices..
i am doing it first time so thats why i don't know which software to use for this purpose, and which software will be nice...

What OS will you be running?

Most spreadsheet programs can be set up, by means of macros or scripts, so that you can enter a list of numbers, then the program will total them and send the output wherever you would like (file, printer, etc) Then you just need the appropriate drivers for the printer for your OS and you're in business.

DWolf