Bowling in PHP

View php here (https://github.com/jacobjlandry/BowlingInPHP)

A long time ago, in a city far, far away...I was a junior developer with big ambitions. I applied for a development role a bit out of my league but I thought I could pull it off. Unfortunately, the very simple coding test I was presented in teh on-site interview completely stumped me.

I have relieved the horror of this day over and over in my dreams. The failure completely haunts me. And so, I have made it my personal goal to solve this coding problem in every new language I pick up.

The problem was simple, and i'm still amazed that it stumped me at that point in my career: Build a bowling calcluator.

The rules:

A frame's score is the sum of all throws in the frame.
A spare is 10 + the next throw
A strike is 10 + the next two throws.
On the 10th frame, if the player gets a spare or a strike, they get a third throw.

Example Input/Output

[
  [ 10 ],        // 30
  [ 10 ],        // 30
  [ 10 ],        // 30
  [ 10 ],        // 30
  [ 10 ],        // 30
  [ 10 ],        // 30
  [ 10 ],        // 30
  [ 10 ],        // 30
  [ 10 ],        // 30
  [ 10, 10, 10 ] // 30
] 
Score: 300

[
    [8, 2],     // 15
    [5, 5],     // 12
    [2, 8],     // 11
    [1, 9],     // 19
    [9, 1],     // 13
    [3, 7],     // 16
    [6, 4],     // 14
    [4, 6],     // 11
    [1,9],      // 19
    [9, 1, 5]   // 15
]
Score: 146

[
    [1, 4],     // 5
    [2, 6],     // 8
    [8, 0],     // 8
    [9, 0],     // 9
    [10],       // 13
    [1, 2],     // 3
    [10],       // 28
    [10],       // 20
    [8, 2],     // 15
    [5, 5, 2]   // 12
]
Score: 121

If you click the link you can see my solution in PHP, and I'll update the description here shortly to include some explanations on what I chose to do.