Does Zoho Checkout support discount coupons?

One Time: Applied once , during checkout.
Forever: Applied on all payments in a recurring payment and once for one-time payments.
Limited Number of Times: Applied on the specified number of successive payments in a recurring payment and once in a one-time payment.

Yes, You can create multiple discount coupons and associate it to your payment pages. To create a coupon:

Go to the Coupons tab on top of the page.
Click + New Coupon button on the top right corner of the page. If you haven’t created any coupons yet, click Get Started.

New Coupon

Field	Description
Coupon Name	Name of the coupon.
Coupon Code	The code that your customers can use to avail the discount.
Discount	The discount that is applied. Can be a percentage of the total amount or a flat amount.
Redemption Type	One Time : Applied once, during checkout. Forever: Applied on all payments in a recurring payment and once for one-time payments. Limited Number of Times: Applied on the specified number of successive payments in a recurring payment and once in a one-time payment. Know more.
Valid Upto	A date after which the coupon cannot be redeemed.
Maximum Redemption	A limit for the number of times the coupon can be redeemed.