both the first are actually 50% discount:

Pack 1:

1x seal=125, 7x myoboku=7x10=70

Total=195>2x88=176

Pack 2:

1xseal=125, 10 x cave key=10 x 13=130, 5 x med refine=5x25=125

Total=380 > 2x188=376

You have to remember that the discounts are based on shop prices, not what we c*ually get the items for.