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	$92.90	12.705%	$104.7029	$104.70	$104.70	$104.70
Purchase #2	$238.53	7.231%	$255.7781	$255.78	$255.80	$255.80
Purchase #3	$182.41	5.779%	$192.9515	$192.95	$192.95	$193.00
Purchase #4	$88.73	3.563%	$91.8914	$91.89	$91.90	$91.90
Purchase #5	$18.64	8.762%	$20.2732	$20.27	$20.25	$20.30
Purchase #6	$89.86	13.421%	$101.9201	$101.92	$101.90	$101.90
Purchase #7	$236.51	12.667%	$266.4687	$266.47	$266.45	$266.50
7 purchase totals =	$947.58		$1,033.9859	$1,033.98	$1,033.95	$1,034.10