Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$194.96	5.417%	$205.521	$205.52	$205.50	$205.50
Purchase #2	$8.98	11.498%	$10.0125	$10.01	$10.00	$10.00
Purchase #3	$117.91	8.211%	$127.5916	$127.59	$127.60	$127.60
Purchase #4	$49.43	13.475%	$56.0907	$56.09	$56.10	$56.10
Purchase #5	$191.39	8.768%	$208.1711	$208.17	$208.15	$208.20
Purchase #6	$101.37	13.822%	$115.3814	$115.38	$115.40	$115.40
Purchase #7	$32.74	8.805%	$35.6228	$35.62	$35.60	$35.60
7 purchase totals =	$696.78		$758.3911	$758.38	$758.35	$758.40