Answer: While the Sales Tax information available in Payment Net can be useful, the data presented is only as good as that sent by the merchant.
Transaction detail is presented in three different levels. Level 1 is the most basic information - merchant name, transaction date, amount, etc. Level 2 allows the merchant to send sales tax information. Level 3 enables the merchant to pass line item detail (i.e. how many pencils you bought, unit price, etc.) or travel-related addendum information. All merchants that accept credit cards pass Level 1 data. A much smaller percentage passes Level 2 and 3 data.
Due to the transaction detail levels, you will not always be able to determine electronically that sales tax has been charged. Sales tax information that IS passed is either automatically populated by the more sophisticated merchants or manually entered by those less so. Additionally, clerks may just be tabbing through fields during the purchase and inadvertently enter some information in the sales tax field that is inaccurate.
The most reliable source for this information is the original receipt or invoice presented by the merchant.
Taxes: If you are charged tax, make one attempt to recover the tax with the vendor and get it credited back to your account. Document your efforts.