To find the percentage of heads, we can use the formula:
\[ \text{Percentage of heads} = \left( \frac{\text{Number of heads}}{\text{Total flips}} \right) \times 100 \]
In this case, Dave flipped the coin 12 times and got heads 5 times. Plugging in those values:
\[ \text{Percentage of heads} = \left( \frac{5}{12} \right) \times 100 \]
Calculating \( \frac{5}{12} \):
\[ \frac{5}{12} \approx 0.4167 \]
Now, multiply by 100:
\[ 0.4167 \times 100 \approx 41.67 \]
Finally, rounding to the nearest whole number gives:
\[ \text{Percentage of heads} \approx 42% \]
Thus, the result is \( \boxed{42} \).