Many calculations involve money.
Coins and Notes
In New Zealand, the coins and notes available are as follows:
Coins

5cents

10cents

20cents

50cents

$1

$2

Notes

$5

$10

$20

$50

$100

Because the smallest coin is worth 5 cents, amounts of money often have to be rounded to the nearest 5 cents.
e.g.
51 cents and 52 cents would be rounded down to 50 cents
53 cents and 54 cents would be rounded up to 55 cents
56 cents and 57 cents would be rounded down to 55 cents
58 cents and 59 cents would be rounded up to 60 cents
This system is called Swiss Rounding and is used by most shops and supermarkets in New Zealand.
If several items are being purchased the rounding is done on the total cost of the items.
I go to the supermarket and buy 5 bars of chocolate 
Total spent 
How much change would I get from $15 (i) 7 packets of soup at $1.94 each? (ii) 6 eggs at $3.86 per two dozen? 
7 × 1.94 + 3.86/4 = $14.55
Change = $15 − $14.55 = $0.45 