Variable coupon for Constant Price

We offer a subscription service for a monthly shipment of products.
The actual prices of the cumulative products will always total to more than the $59.95 subscription price.

I would like to use a coupon that looks at the order total and creates a coupon that lowers the final price to $59.95. How can I do that?

Thanks.

I have not thought of that. No, it is not possible to set the price of the order total with the use of a coupon. This might be possible with purchasing rules: https://polishedgeek.com/paid-extensions/virtuemart-purchasing-rules/overview-a-features.html?amigosid=3

If I can't have a "variable coupon" can I create one on the fly that the user could post in an update screen that would have the same effect?

For example, the user has filled out his cart and is ready to check out.
At that moment we know that the total is $62.27.

When the page is submitted, can we create a new coupon for the difference between $62.27 and $59.95 that would report back its number and be available for use on the next update screen?

Upon entry, it would have the same effect as lowering the price to to the targeted amount.

I have purchasing rules, so please suggest a rule, if one springs to mind.

Thank you.

that seems excessive. If the user then removes or adds items to the cart, you would have to keep creating new coupons. I looked at purchasing rules, I cant get this to work with it.

I think it would make more sense to develop this function. Maybe even hardcoded, if you just need it for one coupon. PM me if you want a customization quote.