If you have Excel 2007,
Check that your data is continuous, with no blank rows or columns. Click on your scores and then select 'Data - Filter'
Using the dropdown that the filter creates at the top of your scores column and select 'Number filters - Top ten'
A 'Top ten Autofilter' dialog will be displayed, reduce the show 10 to 5 and then click on OK.
For earlier versions of Excel add a RANK formula in a new column. Be careful as the scores need to be sorted, usually into descending order. If there are any ties, they will be given the same ranking number and the subsequent rank number will be incremented by the number of ties. (E.g. If there are two scores of 2, ranked as 5. The next score will be ranked as 7, not 6)