public double getPayableAmount(){
        double payableAmount = 0.0;
        payableAmount = getItemsCost(findGroceryItems(items));
        payableAmount += getItemsCost(findNonGroceryItems(items)) * (100 - user.getDiscount()) / 100;
        payableAmount = payableAmount * 0.95;
        return payableAmount;
    }