1 cent per card = $0.60
1% = $1.31 (First Box sold at $2)
2% = $2.62 (Second Box sold at $3)
3% = $0.47 (Third Box sold at $2)
4% = $0.52 (Fourth Box sold at $2)
5% = $0.36 (Fifth Box sold at $2)
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No clue how I was doing those first two percentages....
This box is $8.88 - 6% of that being $0.53 (selling at $2)

Remember no duplicates, oldest set first.