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	$85.27	12.404%	$95.8469	$95.85	$95.85	$95.80
Purchase #2	$178.64	8.649%	$194.0906	$194.09	$194.10	$194.10
Purchase #3	$47.26	10.841%	$52.3835	$52.38	$52.40	$52.40
Purchase #4	$149.84	13.408%	$169.9305	$169.93	$169.95	$169.90
Purchase #5	$195.73	13.710%	$222.5646	$222.56	$222.55	$222.60
Purchase #6	$169.61	13.619%	$192.7092	$192.71	$192.70	$192.70
Purchase #7	$140.48	13.490%	$159.4308	$159.43	$159.45	$159.40
7 purchase totals =	$966.83		$1,086.9561	$1,086.95	$1,087.00	$1,086.90