Feels like homework.
No company I know would be giving exactly 5% and 10% (especially in these times) and in any case with only 17 employees I'm sure it would be faster and easier to just go in and edit the data. Oh, and a company wouldn't care if it was done with one query or two.
And for homework, see rule 1.5 here:
So convince us it's not homework or show us that you have made an effort to solve this.
It's really not hard, honest. Here's a hint: Look at the IF( ) function.
Oh, and in any case it would help a lot to show us the fields in the table that you are using.