Well, yes it is. But one big thing to remember about mobile devices, is that any time you send something from the device to somewhere else you will be costing the user money by using up their airtime. Many users wouldn't be happy with that.
Now, if the connection was bluetooth, then there is no airtime charge. But the device would have to be real near the machine to send the info to. And in that case I would find it much more faster and easier to just type it in directly to the machine that the data is going to. Much bigger screen there.
Usually, for a first project, think in terms of an app that stays on the device, and not need any connectivity. Then work your way up from there.
You can still do a basic checkbook balancing program where the balance is stored in the recordstore, and the user enters withdrawal or deposit from the drop down enters the amount, then that amount gets added or subtracted from the balance in the recordstore. No connectivity needed.
Good Luck
Mark