Translate "Order total"
This post discusses the very same issue. Also, as mentioned in this comment, 


  1) You have to go to this page admin/config/regional/i18n/strings And
  set the language to english..than the translation strings can be made
  to your language.
  
  2) You need to go to admin/config/regional/translate/i18n_string and
  enable
  
  Select text groups  Fields 3) Then the fields are between the normal
  translation page to be able to translate:
  admin/config/regional/translate/translate
  
  4) After adding translation and nothing showing, back to
  admin/config/regional/translate/i18n_string Enable Fields and click
  REFRESH.


Hope this helps.