In my experience, all raises are based off your hiring salary. You start at $100K, you gets several 10% raises, you end up at $100Kx1.10. If you start at $75%, same thing. $75Kx1.10. Rinse and repeat. After 5 years, you are significantly behind based on that initial negotiation. Also, I've read never take the first offer. YMMV.