I agree on normalizing. In other words, store each mark as a separate row.

Student Mark

--------- ------

Bill 88.5

Bill 55.5

Bill 64.4

However if you need to round things, what I might do is use a computed column for this. You can look up syntax, but something like:

Student Mark RoundedMark

--------- ------ --------------

Bill 88.5 89

Bill 55.5 56

Bill 64.4 64