Add To Cart - Coupon option

I was wondering how to get around this - when a customer clicks on ADD TO CART button a Pop Up opens with the options to Continue Shopping or Checkout or Shopping Cart - which is nice - but it bypasses the option for customer to enter a Coupon code if the customer clicks on the Checkout link - ( no option to enter coupon code in checkout process )
So How can I have the customer have the ability to enter Coupon code in the Chekout process - as he would not have seen the Shopping Cart screen ?

Hope I am just missing something -

Dear John,
We can not add the Coupon code adding part to Checkout page. When customers go to checkout, it means that all is ready for Checkout. They must go to Shopping Cart to add coupon code there.
You can give some texts on your site to tell user go to Shopping Cart page to add Coupon code there.
Sincerely, Giang

Understand - I have seen many shopping carts have a coupon code in the checkout -
it is very easy for a customer to add an item - and then just click on checkout - he/she knows what they added int he shopping cart so they proceed to checkout - and therefore totally miss out on the fact they can use a coupon code - seems like there could be an option
to add the ability to add coupon code as a part of the Pop Up windows that gives few options to continue to shop - go to checkout etc - and just add there - add coupon code
I can just hear my client getting complain emails from customers that they could not figure out how to apply a coupon - as most are repeat customers and just Click on Add to Cart ant then select Checkout - why would then need to check shopping cart ?

else there could be an option that just forces all customers to view shopping cart before selecting checkout -
I would not mint that option
I am surprised that more have run into this - as often shop owners email customers with special coupon codes -

Is there an optiion to force customers to view shopping cart prior to Checkout ?