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	$52.81	13.323%	$59.8459	$59.85	$59.85	$59.80
Purchase #2	$62.47	8.696%	$67.9024	$67.90	$67.90	$67.90
Purchase #3	$12.70	11.466%	$14.1562	$14.16	$14.15	$14.20
Purchase #4	$104.57	9.751%	$114.7666	$114.77	$114.75	$114.80
Purchase #5	$177.31	12.265%	$199.0571	$199.06	$199.05	$199.10
Purchase #6	$11.48	7.483%	$12.339	$12.34	$12.35	$12.30
Purchase #7	$207.57	9.295%	$226.8636	$226.86	$226.85	$226.90
7 purchase totals =	$628.91		$694.9308	$694.94	$694.90	$695.00