SQL Server 2008 :: Putting Rows Together To Get Total Times

I am building a query. I have a table with 4 columns and need to try and put the times together. There are some inconsistencies with this, and i'm hoping to exclude them.. Here is a sample table:

Function | Employee | DateTime
--------------------------------------------
1 | 1 | 1/30/2015 1:47 PM
2 | 1 | 1/30/2015 1:49 PM
2 | 1 | 1/30/2015 1:50 PM
3 | 2 | 1/30/2015 1:37 PM
3 | 2 | 1/30/2015 1:39 PM
3 | 1 | 1/30/2015 1:40 PM
4 | 1 | 1/30/2015 1:42 PM
4 | 1 | 1/30/2015 1:45 PM

Function 1 = Clock In Type 1
Function 2 = Clock Out Type 1
Function 3 = Clock In Type 2
Function 4 = Clock Out Type 2

Basically what I need to do is take the time from rows with Function 1 and match it with Function 2 so I can get a total time of the clock in. Function 3 rows need to match up with Function 4 rows so I can get another set of total times. There may be more clock in rows then clock out rows or more clock out rows then clock in rows, and there may be multiple clock ins & outs per day per employee. I'm basically trying to get totals for each Clock In/Out type.