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	$59.41	5.648%	$62.7655	$62.77	$62.75	$62.80
Purchase #2	$138.75	12.228%	$155.7164	$155.72	$155.70	$155.70
Purchase #3	$194.86	10.444%	$215.2112	$215.21	$215.20	$215.20
Purchase #4	$175.64	5.265%	$184.8874	$184.89	$184.90	$184.90
Purchase #5	$137.52	9.142%	$150.0921	$150.09	$150.10	$150.10
Purchase #6	$97.92	8.373%	$106.1188	$106.12	$106.10	$106.10
Purchase #7	$128.38	10.470%	$141.8214	$141.82	$141.80	$141.80
7 purchase totals =	$932.48		$1,016.6128	$1,016.62	$1,016.55	$1,016.60