Change how reward points work

I would like to change how reward points currently use the sub total to use the total.

Ive seen posts on this for earlier versions but cannot find the correct place to implement changes in 2.3.0.2

I would appreciate any help.

You can change that with this extension:

https://www.opencart.com/index.php?rout ... date_added

Or this one:

https://www.opencart.com/index.php?rout ... _license=0

Although this one applies it during checkout, but with total amount

Apologies perhaps I didnt explain what I am looking for.

At present when a customer wishes to use reward points they can only use up to the value of the sub total. So they would still pay any taxes and shipping costs.

I am looking how to change this so that they can apply the reward points to cover everything if they have enough. So reducing the amount due zero.