formula for price increases and markups
 

I have a price book with first tab being the contents page and each
additional tab being product pages. I have it set up where on the contents
page I enter the markup percentage and the corresponding pages show the new
marked up amount. I also need the ablility to change the base prices when a
vendor increase their prices. Is it best to do the price increase on each tab
(and how?), or another way.
Thanks,
DCB