Put An Amount In Program Part Of Check Box And Add Them Up

Im trying to make a fast food program on which the user will input the amount that he has, then he will click on what he wants, by using check boxes. There are 7 different check boxes with 7 different amounts of money. I got an idea on what to do (they will check on what they want and the program will add up the total and there is only one of each item), but im confused on how to put the amount on where the check boxes (in the program area and not the text area) and add them together. After that all I need to do is add everything up, with sales tax, and tell the user if he has enough money or not. But what im confused on is how do I get the check boxes to a amount of money and add them up (all the ones hes checked) I just dont know how to code this part of the program, once I get one done all I have to do is the same for each one, and everything showed be easy after that. But how do I put an amount on a check box and add them all up?