Solution:

You divide $88 (in whole $ increments) into 7 bags as follows:

1, 2, 4, 8, 16, ... , 32, 25.

The first 6 bags contain a total of $63 as per the following series:

2^0, 2^1, 2^2, 2^3, 2^4, ... ,2 ^5.

To gain a better understandstanding, consider the simple case where $12 needs to be divided into a number of bags.
You divide $12 into 4 bags as follows: 1, 2, 4, 5. Then,

If I ask for $:     1     2       3         4        5         6           7  
You give $:       1     2      1+2     4       4+1    4+2     4+2+1