rounding total values including and excluding tax
Budget: £10 – £20 GBP
rounding total values including and excluding tax, Need advise on what approach to follow.
We have 2 items:
Total payable value:
Item 1 costs: 4.29
Item 2 costs: 12
Tax:
For item 1 is: 5%
For item 2 is: 12.5%
Ex Vat (calculated from Total value):
Item 1: 4.0857
Item 2: 10.6667
Now the calculations will go:
Item 1: 4.0857 * 5% = 0.204285 (rounded to 2 digits decimal - 0.20)
Item 2: 10.6667 * 12.5% = 1.3333375 (rounded to 2 digits decimal - 1.33)
Total for basket = 16.29 (as ex vat value is calculated from total value)
Total from ex.vat + taxes: 4.0857 + 0.204285 + 10.6667 + 1.3333375 = 4.289985 + 12.0000375 = 16.2900225 (rounded to 2 digits: 16.29)
If I loose the precision on calcs (for example I calculate tax value from 2 digit decimal number, ex 4.09 * 5%), it will create chain reaction which will enlarge total value to 16.30 (after rounding), so it will create another set anomalies that will affect total value as well.
Anyone has a good idea?
We have 2 items:
Total payable value:
Item 1 costs: 4.29
Item 2 costs: 12
Tax:
For item 1 is: 5%
For item 2 is: 12.5%
Ex Vat (calculated from Total value):
Item 1: 4.0857
Item 2: 10.6667
Now the calculations will go:
Item 1: 4.0857 * 5% = 0.204285 (rounded to 2 digits decimal - 0.20)
Item 2: 10.6667 * 12.5% = 1.3333375 (rounded to 2 digits decimal - 1.33)
Total for basket = 16.29 (as ex vat value is calculated from total value)
Total from ex.vat + taxes: 4.0857 + 0.204285 + 10.6667 + 1.3333375 = 4.289985 + 12.0000375 = 16.2900225 (rounded to 2 digits: 16.29)
If I loose the precision on calcs (for example I calculate tax value from 2 digit decimal number, ex 4.09 * 5%), it will create chain reaction which will enlarge total value to 16.30 (after rounding), so it will create another set anomalies that will affect total value as well.
Anyone has a good idea?