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	$104.38	7.281%	$111.9799	$111.98	$112.00	$112.00
Purchase #2	$220.57	11.414%	$245.7459	$245.75	$245.75	$245.70
Purchase #3	$19.27	3.176%	$19.882	$19.88	$19.90	$19.90
Purchase #4	$42.44	10.492%	$46.8928	$46.89	$46.90	$46.90
Purchase #5	$98.73	10.834%	$109.4264	$109.43	$109.45	$109.40
Purchase #6	$238.26	7.323%	$255.7078	$255.71	$255.70	$255.70
Purchase #7	$214.62	3.567%	$222.2755	$222.28	$222.30	$222.30
7 purchase totals =	$938.27		$1,011.9103	$1,011.92	$1,012.00	$1,011.90