Dynamic percentage in number range

I have a range of prices for multiple products from 1$ to 100$. As well, as I have understanging that for product with cost of 1$ is 15% of margin will apply and for 100$ product – 5%.

Mean that:
1. 1$ product will cost 1 + 1 * 0.15 = 1.15$
2. 100$ product will cost 100 + 100 * 0.05 = 105$

Question is how to calculate margin percentage for all range of numbers between 1$ and 100$?

I have tried to different approaches but in the end I just don’t understand how to make this calculation dynamic, so I will apply formula to a big data range and get the result