AP Invoice Tolerances

When setting AP tolerances up for goods and services, are you able to add a percentage tolerance of 10% for example and then also a total value of max £20.00 tolerance.

This client only transacts in GBP and has no foreign currencies enabled.

Setting 10% as a percetage is fine but if you have a value of 1 million, then 10% of 1 million is far too great. However if the system allows you to say 10% tolerance but with a total value of £20.00 then that would be ideal.

Is anyone aware that this can be done at all?

Thanks