jmc

The height of each nickel is $6.25/100=0.0625$ inches. Divide 8 feet by 0.0625 inches to find that there are $\frac{8\cdot 12}{0.0625}=1536$ nickels in an 8-foot stack. The value of 1536 nickels is 1536\times \0.05=\boxed{\76.80}.