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	$226.40	8.565%	$245.7912	$245.79	$245.80	$245.80
Purchase #2	$92.52	7.501%	$99.4599	$99.46	$99.45	$99.50
Purchase #3	$235.29	7.141%	$252.0921	$252.09	$252.10	$252.10
Purchase #4	$64.97	8.342%	$70.3898	$70.39	$70.40	$70.40
Purchase #5	$81.39	10.285%	$89.761	$89.76	$89.75	$89.80
Purchase #6	$45.72	6.447%	$48.6676	$48.67	$48.65	$48.70
Purchase #7	$59.36	11.454%	$66.1591	$66.16	$66.15	$66.20
7 purchase totals =	$805.65		$872.3207	$872.32	$872.30	$872.50