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	$55.52	7.481%	$59.6735	$59.67	$59.65	$59.70
Purchase #2	$196.99	6.172%	$209.1482	$209.15	$209.15	$209.10
Purchase #3	$94.43	5.735%	$99.8456	$99.85	$99.85	$99.80
Purchase #4	$126.90	8.568%	$137.7728	$137.77	$137.75	$137.80
Purchase #5	$162.29	11.448%	$180.869	$180.87	$180.85	$180.90
Purchase #6	$158.82	4.677%	$166.248	$166.25	$166.25	$166.20
Purchase #7	$221.92	8.113%	$239.9244	$239.92	$239.90	$239.90
7 purchase totals =	$1,016.87		$1,093.4815	$1,093.48	$1,093.40	$1,093.40