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	$59.83	4.352%	$62.4338	$62.43	$62.45	$62.40
Purchase #2	$129.75	13.754%	$147.5958	$147.60	$147.60	$147.60
Purchase #3	$213.62	12.580%	$240.4934	$240.49	$240.50	$240.50
Purchase #4	$10.99	6.870%	$11.745	$11.75	$11.75	$11.70
Purchase #5	$70.40	10.872%	$78.0539	$78.05	$78.05	$78.10
Purchase #6	$36.55	10.229%	$40.2887	$40.29	$40.30	$40.30
Purchase #7	$106.72	9.274%	$116.6172	$116.62	$116.60	$116.60
7 purchase totals =	$627.86		$697.2278	$697.23	$697.25	$697.20