Sales tax issues

Below is an overview of bugs. However, the intention is to create individual issues for any verified issues & move the description to there. As this bug is now an epic it should only be a container for the other bugs, details should not be discussed here & the PRs should be against the other, verified, issues.

1: When there is a change in Contribution line item like Payment instrument, Financial Type etc there is an entry created in civicrm_financial_item table for the change with -ve (using previous financial item) +ve (new financial item). If there is a tax associated with contribution the entries in financial item are incorrect like description, financial account id etc and even in civicrm_entity_financial_txn.entity_id for entity_table = 'civicrm_financial_item'.

2. When we create new contribution using New Contribution Form without priceset with Financial Type Donation (having tax defined for Donation Financial type), civicrm_contribution.tax_amount stores incorrect value.

3. When you try to updated the contribution amount having tax using New Contribution Form, it throws a validation error 'The sum of fee amount and net amount must be equal to total amount' even though the sum of net amount and fee amount is equal to total amount.

4. When there is a change in contribution Financial Type, the entries in financial trxn are created incorrectly which results in unbalance in Balance report.(CRM-19273 fix in QA might resolve this - retest this after applying & testing that)

5. When there is a change in Contribution Financial type and Total Amount in one shot, the entries in financial trxn are created incorrectly which results in unbalance in Balance report. (CRM-19273 fix in QA might resolve this - retest this after applying & testing that)

NB: As of Feb 2, 2017
PR 9340, 9588 closed
PR 9590 merged
PR 9682 open

As of Mar 10, 2017
https://github.com/civicrm/civicrm-core/pull/9590/files and which are addressed by
https://github.com/civicrm/civicrm-core/pull/9589 - has been approved by a reviewer
https://github.com/civicrm/civicrm-core/pull/9682
https://github.com/civicrm/civicrm-core/pull/9683
https://github.com/civicrm/civicrm-core/pull/9684
https://github.com/civicrm/civicrm-core/pull/9685 WIP