changing values!!

I wanted a SIM. Got it for 99. Which is 100-1.
I got this 1 year validity thing. Got it for 95. 100-5.
I paid this guy 200 bucks.
Here i was Trying to continiously remind myself to get the change back as he verified my particulars. But as expected i forgot.
I had walked 10 min away when it struck me like lightening.
Now the dilemma.
Was the walk worth the 5 bucks. (considering that pple completely ignore a Re.)
2 steps forward n then 2 steps back. I decide. 'This is Hard Earned' money.
I reach the place and in an embarassing tone ask him for the 5 bucks.
I think i heard somebody giggle. But i kept steady.
"Do you have Rs. 5 change? " he asked, "I have 10 bucks"
I checked and finding none i refused.
Then there was a market wide search for a 5 rs. coin. Again finding none he came back and handed me the 10 rs. note. You keep it.
If only a bottle of an 'invisible' potion cost 10.