WORKAROUND THAT WORKED FOR ME:  for dual return files (self/spouse):

For all T3s: enter 100% ownership at top and then half of all values into boxes, for each person.  (I also only entered capital gains in box 53, using the same value as line 21, half the total, instead of dividing the time periods).

Then values for line 68140 on T936 were correct and agreed with Schedule 3 line 17600, and I could NETFILE both returns. 

Thank you so much for sharing.  Your entering way works for me, too.  

I got the same error code yesterday.  The first attempt I made at noon just changed the cents to a even amount so there are no round up or round down variance then I saved and resend it but I still got the same error message.  Then I follow your way entering the amount for my share in my return and enter the remaining amount to my spouse account and work for us.

Thanks again. 

I used a similar work around. For T3s and T4s that listed joint spouse/self ownership, listed 100% ownership to spouse and removed self data . I was able to submit tax return. 

Glad to hear that. Thank you for the update!