To find the cost per ounce, you need to divide the total cost by the total number of ounces.
The cost of the bag of chips is $5.99 for 13 ounces.
So the calculation is:
\[ \text{Cost per ounce} = \frac{5.99}{13} \approx 0.46 \]
Therefore, the cost per ounce is approximately $0.46.