Calculating data based on range of years

I am new to this blog.  I have searched everywhere for a solution and cannot find one. 

My issue is I need to calculate the Sum Of data based on future year ranges. For eg: sales amount for 0-5 , 5-10,10-15,15-20...30+yrs. where 0= this month end(12-31-2020) and 5 = same month end after 5 years and so on. I got a daily date table available in a date format. 
Any help would be greaty appreciated.  Please move this to the correct area as I cant figure out how to get this post there.