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	$117.94	8.108%	$127.5026	$127.50	$127.50	$127.50
Purchase #2	$9.37	12.560%	$10.5469	$10.55	$10.55	$10.50
Purchase #3	$68.83	6.430%	$73.2558	$73.26	$73.25	$73.30
Purchase #4	$229.60	11.873%	$256.8604	$256.86	$256.85	$256.90
Purchase #5	$238.36	6.250%	$253.2575	$253.26	$253.25	$253.30
Purchase #6	$100.47	4.182%	$104.6717	$104.67	$104.65	$104.70
Purchase #7	$45.32	10.506%	$50.0813	$50.08	$50.10	$50.10
7 purchase totals =	$809.89		$876.1762	$876.18	$876.15	$876.30