I am looking for a precise term of the "decimal form of percentage" - f.x. 0.35 instead of 35%. It was previously discussed 6 years ago (Correct term for percentage in decimal form) and some good suggestions came up.
I could go with percent decimal or similar, but I wonder if there is a better term. I like the term "per unit" (taken from the field of electrical engineering) because I think it is a logical parallel to percent - though it has a different meaning in its original context.
This isn't a "form of percentage" - in fact, what you are doing is simply not using percentages.
You could describe this as a "proportion", for example "it costs $\$5$ plus tax at a proportion of $0.15$".