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	$55.96	4.820%	$58.6573	$58.66	$58.65	$58.70
Purchase #2	$105.43	12.461%	$118.5676	$118.57	$118.55	$118.60
Purchase #3	$103.30	7.605%	$111.156	$111.16	$111.15	$111.20
Purchase #4	$244.51	7.347%	$262.4741	$262.47	$262.45	$262.50
Purchase #5	$163.49	9.181%	$178.5	$178.50	$178.50	$178.50
Purchase #6	$168.66	3.502%	$174.5665	$174.57	$174.55	$174.60
Purchase #7	$169.38	6.610%	$180.576	$180.58	$180.60	$180.60
7 purchase totals =	$1,010.73		$1,084.4975	$1,084.51	$1,084.45	$1,084.70