Large scale economics

The other day I bought petrol at a Coles servo. I saw they had
Starburst Sucks available for impulse purchase, 3 for a dollar. I
bought 3. The woman behind the counter offered me another 3 for
another dollar, to earn an additional 2c/L discount on the fuel. I
politely declined but later realized that I paid $1.20/L for 60 litres
($72) less 4c/L ($2.40) plus $1 for the lollipops (total $71.60). 3
more lollipops for $1, less 2c/L additional discount ($1.20) means the
deal I turned down was them paying ME 20c to take 3 of their lollipops
away.

Sometimes I am a financial genius.