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	$208.50	3.472%	$215.7391	$215.74	$215.75	$215.70
Purchase #2	$58.45	5.486%	$61.6566	$61.66	$61.65	$61.70
Purchase #3	$244.59	3.740%	$253.7377	$253.74	$253.75	$253.70
Purchase #4	$245.54	5.105%	$258.0748	$258.07	$258.05	$258.10
Purchase #5	$45.79	5.623%	$48.3648	$48.36	$48.35	$48.40
Purchase #6	$88.89	6.720%	$94.8634	$94.86	$94.85	$94.90
Purchase #7	$124.62	5.152%	$131.0404	$131.04	$131.05	$131.00
7 purchase totals =	$1,016.38		$1,063.4768	$1,063.47	$1,063.45	$1,063.50