Each mod set gives the bonus so 2.5% (5% if maxed) for each set so total 15%. However you might be better to go crit and crit dmg since 4 crit dmg mods give 30% to crit dmg and you can negate that 10% crit loss with secondary stats on mods.
For instance on lando since he has a latent ability that gives him extra crit chance you might be wise to get crit chance and crit dmg with primary stat on triangle as crit dmg to push you to 216% crit dmg, also if he's paired with say leia or raid Han he will have that crit buff a lot making crit mods less valuable than crit dmg.
What I'm saying is mods can be very dynamic and you can swap them based on your conditions but also keep in mind what you need from that toon within your group, all these should be factored when setting up mods