This took me forever to find online, so I’m posting it here for the next helpless soul. If you need to round datetimes coming out of sql to the nearest 5 minutes, here you go.
dateadd(mi,(datepart(mi,dateadd(mi,1,DateTimeColumn))/5)*5,dateadd(hh,datediff(hh,0,dateadd(mi,1, DateTimeColumn)),0))