Since your code executes about once every 5 seconds
Code:
LoopCount VAR BYTE
LoopCount = 0

' ------------------
' Rest of code goes here
' ------------------

LoopCount = LoopCount + 1

If LoopCount = 59 THEN   ' 60 times 5 seconds = 300 seconds = 5 minutes.
  Hserout [dec TimeH,":",dec TimeM," ",DEC(TempC/10),".",#TempC dig 1,13,10]
  LoopCount = 0
ENDIF
/Henrik.