So i emailed qdabra support, never heard back from anyone.
I decided to spend some time trying to dechiper this problem as i am pressed to get this project finished. AND BOOM, the answer hit me. here it is for anyone ever encountering the same problem :
number(substring(string(round((my:o_labour + my:o_expense) * 100) * .01), 1, string-length(substring-before(string(round((my:o_labour + my:o_expense) * 100) * .01), ".")) + 9))
once i nested the rounding formula in the truncating decimal formula, i no longer experienced any more long decimal sums from a simple addidtion calculation. I've applied this to all fields or rules that invlove a calculation.
for a little more indepth syntax with copying of data by respective row:
number(substring(string(round((../../../../my:zumi/my:effort[../my:row = current()/../@line_nbr] + ../../../../my:zumi/my:effort_to_complete[../my:row = current()/../@line_nbr]) * 100) * .01), 1, string-length(substring-before(string(round((../../../../my:zumi/my:effort[../my:row = current()/../@line_nbr] + ../../../../my:zumi/my:effort_to_complete[../my:row = current()/../@line_nbr]) * 100) * .01), ".")) + 9))
I hope this helps anyone who ends up in this situation.