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	$91.87	4.492%	$95.9968	$96.00	$96.00	$96.00
Purchase #2	$153.35	11.462%	$170.927	$170.93	$170.95	$170.90
Purchase #3	$138.31	13.137%	$156.4798	$156.48	$156.50	$156.50
Purchase #4	$146.47	3.719%	$151.9172	$151.92	$151.90	$151.90
Purchase #5	$39.40	3.502%	$40.7798	$40.78	$40.80	$40.80
Purchase #6	$79.93	10.459%	$88.2899	$88.29	$88.30	$88.30
Purchase #7	$176.52	7.673%	$190.0644	$190.06	$190.05	$190.10
7 purchase totals =	$825.85		$894.4549	$894.46	$894.50	$894.50