Calculating a Running Total

I have some buttons that you press and it makes different types of toppings appear on a burger, but I’d like there to be a cost attributed to each topping and a running total showing the cost in the bottom right corner. The cost must be deductible if the toppings are removed.

Could someone either point me towards a useful tutorial or lend a hand helping out a newb? I would really appreciate it. :slight_smile: