If you change your temp basal adjustment to units, you can adjust your temp increments at 0.05 units per hour. Would this still not be a fine enough adjustment?
First created the pre-set temp basals you want to have at “percent”.
Next, go to:
Settings >System Setup > Bolus/Basal/calcs.
Change temp basal to units/hour instead of percent
This is the best of both worlds. Use the presets you already have that use percentage for longer temps, where the percentage is constantly changing the normal basal value for each hour.
Or use the units/hour temp basal for any fine-tuning you want.
For example, you can change from 0.65 units/hour to 0.70 units/hour or 0.60 units per hour. That is about as fine-tuned as you could ever want!
Let me know if you have questions about what I am describing.