Sage is based on four prices:
Why Sage did not base on markups I do not know, each company has their own level of markups: example
Sales cost + 55%
Trade cost + 45%
Retail cost + 65%
It would have been far simpler to manage using this and save a lot of time and energy editing single items!
All of these items need to be in Company Setup, as policy decisions are made there.