making shoppping counter software ,getting started help

the software is relating to counter in shops or stores , the mail archivement of this new project is to
calculate prices
sub total
item list
logs by date
additional = barcode reader and read the price , how do i make custom barcode how will software reconize barcode.


this i never done before and willing to make, i know that the calculation bit can be little easy using many calulator soft but i wish to se replies from anyone willing to show me some examples or ideas how to get started what is best method to use for shop software , simple tool