Not many records survive from that era, we will probably never know for sure.
The only advice I can give you is to go to a grocery store, check the price of the candy bars and subtract maybe a nickel.
25 cents
The average cost of a candy bar is around $0.99 without tax.
A nickel.
25c
That depends on what sort of candy bar it is, where you live, when you buy the candy and in which specific store you shop.
50 cents
10 cents
About 2 shillings.
5 cents
12 cents
if you're buying 2 candy bars, then 1.00.
I don't know for sure, but I think the average cost for a candy bar was around 5 cents.