Fruit shop profit

This task is about rounding and estimating. 
Mr and Mrs Richmon at their fruit store
Mr and Mrs Richmond own a fruit store.  Each month they both estimate their shop profits. 

Question 1Change answer

a)  i)  Complete Mr Richmond's table below to show each amount rounded to the nearest $100, then
     ii) Add up the rounded amounts and write in the total estimate.
Week Amount of takings Rounded amounts
1 $2,842 i) $  
2 $3,125 i) $ 
3 $3,633 i) $ 
4 $2,287 i) $ 
  Total ii) $ 

Question 1Change answer

b)  Write in the rounded amounts that Mrs Richmond used to get her $12,000 total in the table below.
Week Amount of takings Rounded amounts
1 $2,842 $ 
2 $3,125 $ 
3 $3,633 $ 
4 $2,287 $ 
5 Total $12,000

Question 1Change answer

c)  Explain why or when you would use rounding instead of exact calculations in some situations.