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	$182.29	12.638%	$205.3278	$205.33	$205.35	$205.30
Purchase #2	$6.66	10.679%	$7.3712	$7.37	$7.35	$7.40
Purchase #3	$10.49	4.597%	$10.9722	$10.97	$10.95	$11.00
Purchase #4	$107.46	4.194%	$111.9669	$111.97	$111.95	$112.00
Purchase #5	$165.33	4.121%	$172.1432	$172.14	$172.15	$172.10
Purchase #6	$49.74	6.249%	$52.8483	$52.85	$52.85	$52.80
Purchase #7	$202.82	4.292%	$211.525	$211.53	$211.55	$211.50
7 purchase totals =	$724.79		$772.1546	$772.16	$772.15	$772.10