Okay, let's try this out, on a perfect game. (The extra balls for the strike in the tenth frame are in the 'eleventh' and 'twelfth' frames, respectively.)

      +-----------------------------------------------+
Frame | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 |11 |12 |
      +-----------------------------------------------+
Tally |  X| X | X | X | X | X | X | X | X | X | X | X |
      +-----------------------------------------------+
Score | 30| 60| 90|120|150|180|210|240|270|300|310|320|
      +-----------------------------------------------+
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The extra balls should be counted only for their bonuses in the previous frames. They do not get counted on their own. Thus, the correct score for a game of X 0 / X 0 / X 0 / X 0 / X 0 / X is 200, not 210.