Elemental Resistance Variant Rule System

I have always felt that elemental resistances in D&D and Pathfinder should be in multiples of 6 instead of 5, if only because damage is typically rolled with D6s. A creature with strong enough ties to fire to be resistant to it should be able to stand in a small campfire and never risk taking 1 point of damage. It should be able to sleep comfortably in the fire if it wishes and wake up unharmed, rather than taking tiny amounts of fire damage every 6 rounds. It should feel at home in the fire rather than be anxious about when it is going to flare suddenly.
It also doesn't make sense to me that a creature who is extremely resistant (energy resistance 20+) to fire that falls in lava or gets breathed on by an elder red dragon and takes 50, 100, or maybe more fire damage would burn to ash almost as fast as an ordinary human. The body of such a creatureshould should be significantly less damaged by the extreme heat. The creature should have a much higher chance of surviving and experience much less pain.
So I devised an alternate system for handling elemental resistances. Note: This has not been playtested.
All resistances are now in multiples of 6 instead of multiples of 5. Resistance 5 becomes resistance 6, resistance 10 becomes resistance 12, and so on. Additionally, these values also have a corresponding percent value. If the percent value would reduce the damage by more than the numeric value, it is used instead. For these percentages, I took the (multiple of 5) resistance value and multiplied it by 3.
5  ->  6 or 15%
10 -> 12 or 30%
15 -> 18 or 45%
20 -> 24 or 60%
25 -> 30 or 75%
30 -> 36 or 90%
Immune
If I remember correctly, any resistance beyond 30 just becomes immunity. Whether that is official or a house rule, I don't remember, but it is how I play. If you don't use that rule, you may wish to change the percentage values to better suit your play style.
I understand this would be a buff to elemental resistances, though, as with most things, I only do it for flavor. Still, it may make elemental damage dealt by your players less effective. If desired, you could only use this variant for your players while using standard rules for everyone else. Or if your players want an extra challenge, only use it for everyone else.