I'm a software developer and I've been researching USA state sales tax and have found something out that I'm not sure too many people are aware of:
Every state has a different method of rounding sales tax (at least until recently).
The three methods (that math allows) are:
- Round
- Floor
- Ceil(ing)
Most states use rounding, thanks to the Streamlined Sales Tax Project. I think 24 states use the method outlined in that.
The other states are not participants of the SSTP, but still many states use rounding.
There exist API services for figuring sales tax, but only for the rate, not the method (as far as I can tell from the returned JSON).
I believe the liability is on the programmer, unless he develops an option for the user to select one of the three methods.
Please correct me if I'm wrong anywhere; looking for input.
I've read state documents from 2002-2012 in which states used to floor or ceil, but they changed the method to rounding.
Short of calling each state's Department of Treasury, I'm not sure how to know which state does what.
Every state has a different method of rounding sales tax (at least until recently).
The three methods (that math allows) are:
- Round
- Floor
- Ceil(ing)
Most states use rounding, thanks to the Streamlined Sales Tax Project. I think 24 states use the method outlined in that.
The other states are not participants of the SSTP, but still many states use rounding.
There exist API services for figuring sales tax, but only for the rate, not the method (as far as I can tell from the returned JSON).
I believe the liability is on the programmer, unless he develops an option for the user to select one of the three methods.
Please correct me if I'm wrong anywhere; looking for input.
I've read state documents from 2002-2012 in which states used to floor or ceil, but they changed the method to rounding.
Short of calling each state's Department of Treasury, I'm not sure how to know which state does what.