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	$99.77	11.460%	$111.2036	$111.20	$111.20	$111.20
Purchase #2	$20.72	10.216%	$22.8368	$22.84	$22.85	$22.80
Purchase #3	$25.27	7.290%	$27.1122	$27.11	$27.10	$27.10
Purchase #4	$173.43	10.353%	$191.3852	$191.39	$191.40	$191.40
Purchase #5	$145.75	11.648%	$162.727	$162.73	$162.75	$162.70
Purchase #6	$104.38	4.511%	$109.0886	$109.09	$109.10	$109.10
Purchase #7	$94.62	9.277%	$103.3979	$103.40	$103.40	$103.40
7 purchase totals =	$663.94		$727.7513	$727.76	$727.80	$727.70