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	$195.67	6.332%	$208.0598	$208.06	$208.05	$208.10
Purchase #2	$151.33	4.473%	$158.099	$158.10	$158.10	$158.10
Purchase #3	$80.65	6.444%	$85.8471	$85.85	$85.85	$85.80
Purchase #4	$160.99	3.444%	$166.5345	$166.53	$166.55	$166.50
Purchase #5	$205.27	11.136%	$228.1289	$228.13	$228.15	$228.10
Purchase #6	$104.26	5.596%	$110.0944	$110.09	$110.10	$110.10
Purchase #7	$57.57	4.112%	$59.9373	$59.94	$59.95	$59.90
7 purchase totals =	$955.74		$1,016.7010	$1,016.70	$1,016.75	$1,016.60