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	$205.44	13.811%	$233.8133	$233.81	$233.80	$233.80
Purchase #2	$161.68	6.693%	$172.5012	$172.50	$172.50	$172.50
Purchase #3	$116.53	9.762%	$127.9057	$127.91	$127.90	$127.90
Purchase #4	$207.30	7.424%	$222.69	$222.69	$222.70	$222.70
Purchase #5	$118.92	8.694%	$129.2589	$129.26	$129.25	$129.30
Purchase #6	$225.93	3.363%	$233.528	$233.53	$233.55	$233.50
Purchase #7	$242.72	8.594%	$263.5794	$263.58	$263.60	$263.60
7 purchase totals =	$1,278.52		$1,383.2765	$1,383.28	$1,383.30	$1,383.30