give customer some discount when he bought over 200 dollars

hi
I am selling drink,I would like to give customers half discount when they buy the forth glass of drink after having ordered three glasses of drink every time.

is there such commercial extension?

thanks

If it is the same drink you can use the built in bulk quantity
if not you can search the marketplace for something perfect for your needs
https://www.opencart.com/index.php?rout ... t%20module

thanks for reply,my purpose is to encourage customer to order more amount and more times:
after a customer has order serveral times or the total of all his history orders has over certain amount,he will auto-received a discount coupon.
I am searching ,but havenot found a similar commercial extension

now I think if I can make reward points have expired date,it would satisfy all my requirement.

Ultimate Fee/Discount can do this, it has a "Past Orders" rule that lets you give a discount based on a customer's past orders. You can limit them by number of days, quantity, total, product, and order status, so you can target only "Complete" orders for certain products in the last X days, if you want.

Feel free to take a look at the screenshots and demo site, and if you're interested let me know at www.getclearthinking.com/contact if you have any further questions.