So, is this like a school project or something? This study is assuming that
there is an existing system, and therefore database it relies on, in place. If
that is true then it doesn't make sense to design a new database from scratch
without at least looking at the existing one. Anyway it seems that at the very
least you should have a table for your inventory with

id : int Primary Key
price : decimal // or float if you prefer
item number : int //though they may have letters, spaces, or dashes so you may
have to instead use varchar
color: varchar
size : varchar
misc_info : blob

I can't say I'm really sure what belongs in the retail transaction file. I would
assume a simple log of transactions in which case every transaction would have
it's own ID in order to facilitate returns and invoices. As for the department
number it's not clear where that goes. I also have a problem with

--"items that are either too small or too bulky to carry price tickets are
assigned article numbers. Goods sold or returned must bear an article number in
order to be properly processed."

As it implies that items sold may, or may not have an article number, but only
items with article numbers can be returned.