Volume of cardboard box = L x B x H = 28x18x22 =11,088 cubic centimeters
Volume of storage cube = LxLxL= 16x16x16 = 4,096 cubic centimeters
The extra space = 11,088 - 4,096 = 6,992 cubic centimeters
The cost to fill the extra space = 6992 x 0.002 = $13.984 approximately $13.98