var cashRegister = {
    total:0,
    add: function(itemCost){
        this.total += itemCost;
    }
};

var eggs = 0.98;
var milk = 1.23;
var magazine = 4.99;
var chocolate = 0.45;

var list = [eggs, milk, magazine, chocolate];
//call the add method for our items
for (i = 0; i < list.length; i++) {
    cashRegister.add (list[i]);
}

//Show the total bill
console.log('Your bill is '+cashRegister.total);