you know how the game rounds down right...

does that kick in with a spell like guardian?
9 protection gives me 38% chance to block, 10 is at 40%
so would 9 protection round down to 30% or stay at 38%?
wanting to know this jus in case 10 protection would be more effective then 9

Just tried it:

8=36% chance to block attacks
9=38% chance to block attacks
10=40% chance to block attacks

I had to read 3 times to get what you meant.
The round down only applies to decimals i believe so 12.5 would be 12.

Exactly...

Only decimal values are rounded down.