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	$62.30	5.299%	$65.6013	$65.60	$65.60	$65.60
Purchase #2	$65.34	10.659%	$72.3046	$72.30	$72.30	$72.30
Purchase #3	$140.35	13.840%	$159.7744	$159.77	$159.75	$159.80
Purchase #4	$54.50	11.365%	$60.6939	$60.69	$60.70	$60.70
Purchase #5	$114.60	5.430%	$120.8228	$120.82	$120.80	$120.80
Purchase #6	$71.88	3.110%	$74.1155	$74.12	$74.10	$74.10
Purchase #7	$63.45	13.659%	$72.1166	$72.12	$72.10	$72.10
7 purchase totals =	$572.42		$625.4291	$625.42	$625.35	$625.40