Barcode Scanner / Cash Registers

[M. N. Khan]

Hello all.
Has anyone worked with java and cash registers / barcode scanners etc..?
I need to know which ones are compatible with java and linux, so I can buy the right 
ones.
I will be writing a java program on linux for a Retail clothes company who want a 
complet stock and sales software.
Any ideas?  Do I need any special drivers?  Are there any modules in java that I need?
Any other suggestions?
Thanx