I agree with Ben. You can use "overall" only when there are additional expenses involved. When you buy a new car, you don't only pay the sticker price for the car itself. There are options, extras, you have to register it, get insurance etc. If you told me you bought a new car for $10,000 I may ask you, "And what did it cost you overall?" to which you say, "Altogether, it was almost $12k."
At the checkout: "What is the total?", "What's my total?", "How much is it?", "What do I owe you?", "What's the damage?" (informal and trying to be funny).