The sum of the numbers $3.99 + 5.50 + 6.70 + 6.70 + 8.99 + 8.99 + 9.48 + 9.68$ is calculated as follows:

$3.99 + 5.50 + 6.70 + 6.70 + 8.99 + 8.99 + 9.48 + 9.68 = 59.03$

So, the total sum is 59.03.

Would you like more details or have any questions?

Here are 8 related questions:

1. What is the average of the numbers provided?
2. How would you calculate the sum if one number were missing?
3. What is the median of these numbers?
4. How can we calculate the sum of these numbers using mental math tricks?
5. What is the range of these numbers?
6. How would the sum change if each number were increased by 1?
7. Can you calculate the sum of these numbers if they were squared?
8. What would the sum be if you only added the even-positioned numbers?

Tip: When adding multiple numbers, it can be helpful to group numbers that add up to a round figure (like 10) to make mental math easier.