Welcome to Target and The Break Room! One of your training days will be devoted to cashiering. Check out our workcenter guides and the Wiki and tailor to how your store does things. But wait until after your training starts - you don't want to get overwhelmed with all that information. We have coffee, baked goods, and age-restricted beverages in the shoutbox, so stop in.
I'm sure you'll do great. The busy retail environment can be intimidating at first, but you learn to embrace it. When I was hired as a cashier 3 years ago, I had five "training shifts" over two weeks (albeit with limited availability because of school), but the cashiering tutorial was in the first shift and the rest of the shifts were essentially for practice and completing my learning plan. When I trained in hardlines, I had a few days of training shifts.