I develop some midi, set the tempo to 90 BPM, then work with the tempo view to account for a couple of holds (fermata I guess is the proper musical term) and maybe a ritard of the tempo at the end.
 
After I practice at 90 for a while and become more proficient, I want to goose it up to say 108 BPM.  So I change the tempo to 108 and it starts out fine, but once I hit the first hold, the tempo map makes it change back to 90. 
 
Is there anyway to make the tempo map relative to the initial tempo specified on the transport?  Do I have to use groove clips to do this?
 
..    Tony
..    HP Pavilion P6000, Sonar X2 Studio (build 306) x64, Tascam US-144 mkII
 

Sorry, there is no way (AFAIK) to apply an offset to the entire tempo map at once. You have to redraw the tempos across the board, manually adjusting each tempo change. 

What I do to avoid that problem is to not enter any tempo changes (e.g. ritards) until I've settled on the overall tempo of the song. It's a hokey workaround, as it's clumsy rehearsing with a song that's missing important tempo changes.

Well, thanks.  I'm never sure if I'm just missing some trick.  So now I'll take your word for it that it cannot be done.  I can quit wasting time trying to figure it out.  I'm a little bummed out, I was hoping this might have been an improvement making it worth my while to upgrade from Home Studio.
 
 

I don't think there's been much upgrading in MIDI editing since the 1980's. 
I started with HS back in 2004 and I now use 8.5 and as far as midi goes I see no changes. Only improvements are the additional soft synths. 

Why on earth the tempo does not show on the events list is one mystery to me. Back in the 80's that was where you did a lot of editing of the tempo,  CC and , Programs changes. All the data should be on that list. 
For a while I was using a free MIDI editor just to work on this kind of stuff. I eventually just gave in to using Sonars convoluted system which I have under control now,, but I can see room for improvement which won't probably happen. 

MIDI has been ignored by a lot of DAWS for years for some reason.
I know it's not new or hip and doesn't have shiny graphics...