When multiple people shoot the same score they all share the lowest place for that score. The next lowest score would be the next place plus all the ties. Hard to explain, easy to show. Check out the results below:
1. Bob 65 (-5)
2. Fred 66 (-4)
3. Billy 66 (-4)
4. John 66 (-4)
5. Jeff 66 (-4)
6. Ray 66 (-3)
7. Phil 66 (-3)
8. Greg 66 (-2)
If players didn't share the highest tied place then you would have a leaderboard that looks like this. While accurate in its listing it may give the impression that Jeff's 66 is not as good as Billy's 66. A 66 is a 66, so everyone who shoots 66 gets 2nd place.
1. Bob 65 (-5)
2. Fred 66 (-4)
2. Billy 66
(-4)
2. John 66 (-4)
2. Jeff 66 (-4)
6. Ray 67 (-3)
6. Phil 67 (-3)
8. Greg 68 (-2)
When you have shared ties it eliminates the positions below. In this example we have 4 players tied for 2nd which eliminates 3rd, 4th and 5th because the 4 players in 2nd place occupy those spots. On the PGA Tour the ties for 2nd would receive prize money that was equivalent to 2nd place + 3rd place + 4th place + 5th place divided amongst the 4 players equally.
The same thing happens with the tie for 6th place. Since 2 players occupy 6th place it eliminates 7th place and puts Greg 8th out of 8 players.
Hope that answers the question. =)