To determine the volume of the nickels in a $2 roll, we need to first find out how many nickels are in the roll.
A roll of nickels contains 40 nickels, as each nickel is worth 5 cents and $2 worth of nickels is:
\[ \text{Number of nickels} = \frac{200 \text{ cents}}{5 \text{ cents per nickel}} = 40 \text{ nickels} \]
Next, we can calculate the volume of 40 nickels. The volume of a single nickel is given as 0.719 cm³. Therefore, the total volume of 40 nickels is:
\[ \text{Total volume} = \text{Number of nickels} \times \text{Volume of one nickel} = 40 \times 0.719 \text{ cm}^3 \]
Calculating that gives:
\[ \text{Total volume} = 40 \times 0.719 = 28.76 \text{ cm}^3 \]
Therefore, a $2 roll of nickels has a volume of:
\[ \boxed{28.76} \text{ cm}^3 \]