The "base" gathering chance cap is 95%, plus the difference between your level and the item's level.

Level 60 gathering level 54 items? 95% + 6% = 101%, capped at 100%.
Level 56 gathering level 54 items? 95% + 2% = 97% max.
Level 60 gathering level 60 items? 95% + 0% = 95% max.

Of course, you can always use skills to bump that, this only applies to the base gathering chance as determined by your Gathering score.