OpenCart is best Open Source Solution for Shopping Cart. I was working with it before couple of days and it shows Order Total to zero on Shopping Cart page. Later I came to know that Order Total is always zero irrespective to any Page. Means If I go to Checkout Page than also Order Total comes to Zero. After little search, I got a solution and it is due to Sub Total module is disable from admin panel. You just need to enable Sub Total module from Admin. If you are not aware where the Sub Total module is than just follow below steps.
1. Login to Admin Panel
2. Go to Extensions > Order Total and Find Sub Total
3. Edit it, Enable it, Save it.
4. You are Done.