B: Miss, you have underpaid me. "You didn't give me all"? This would not be natural and is incorrect, however you could say "you haven't given me enough"

I would just keep my hand out, palm up, with the $5 she handed me resting on my palm, to indicate that I am expecting more. If she starts to walk away, then I would say, "Ummmm, excuse me, ma'am. The item costs ten. You owe me five more." Perhaps she thought she gave you a $10 bill instead of a $5 bill. With US dollars, it is quite easy (especially for tourists) to make a mistake because the bills are all of the same size and colors.

Some options: "Miss, you only gave me 5 dollars. The price is 10 dollars." Or, "Miss, the total is 10 dollars. You only gave me 5 dollars." Or, "Miss, this item is 10 dollars. You only gave me 5 dollars."