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	$105.66	11.387%	$117.6915	$117.69	$117.70	$117.70
Purchase #2	$221.69	4.350%	$231.3335	$231.33	$231.35	$231.30
Purchase #3	$209.91	6.239%	$223.0063	$223.01	$223.00	$223.00
Purchase #4	$50.50	8.201%	$54.6415	$54.64	$54.65	$54.60
Purchase #5	$98.41	13.127%	$111.3283	$111.33	$111.35	$111.30
Purchase #6	$196.95	5.575%	$207.93	$207.93	$207.95	$207.90
Purchase #7	$192.57	8.443%	$208.8287	$208.83	$208.85	$208.80
7 purchase totals =	$1,075.69		$1,154.7598	$1,154.76	$1,154.85	$1,154.60