java problem.

i have an array list call item order inside it it has [Pencil : 14.50, Rubix Cube : 10.00, Laptop :1300]

my question is here i need to calculate the total of these items with exception

if they are member and they purcase more than 20 dollars they will get 15 percent discount;

the problem is the assignment need to calculate the array list one by one so first initiation from user, user wanted to buy pencil 14.50 he does have account but dont get discount and total will stay at 14.50, second initiation the user want to buy rubix cube 10 dollars. now the total is 24.50 they will get discount so the total will will be 20.82. then the last is he wants to buy laptop total is 1324.50 and they will get discount and total will be 1125.82