Tangerine cut-off time?

Posting a payment and processing it (showing on transaction list and updating your balance) are different things my friend.
And destination does matter: are you paying a Tangerine credit card, a Scotia credit card or another?

Generally for all major bank to 3rd-parites it should be somewhere 3.30 to 4pm pm for all AFTs including bill payments for.
Tangerine being not a Tier1 bank leverages Scotia's backbone for CPA exchange - so Tangerine to Tangerine or to Scotia should be same day as receiving (not processing)

Most reasonable credit card operators consider the date of payment from initiating site as the post-mark date but processing the payment takes another 1-2 in my experience.

How do I cancel or recall a bill payment?

Payments made online or through our Mobile Banking app
You have until 10:00pm of your bill payment date to cancel your payment and have the transaction reversed right away. Here's how:
1. Log in, click or tap your Chequing Account, and find the bill payment transaction that you’d like to cancel.
2. Select 'Delete Payment' and confirm.

If you’d like to recall a payment after 10:00pm:
1. Log in, click or tap your Chequing Account, and find the bill payment transaction that you’d like to recall.
2. Select the 'Recall Payment' button for instructions.

Payments made through your Client Card with Visa* Debit
Changes to your payments made using your Client Card with Visa* Debit need to be arranged with the merchant. Contact your merchant for details. For transactional disputes, please give us a call.