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	$84.78	7.258%	$90.9333	$90.93	$90.95	$90.90
Purchase #2	$138.54	9.439%	$151.6168	$151.62	$151.60	$151.60
Purchase #3	$209.99	3.499%	$217.3376	$217.34	$217.35	$217.30
Purchase #4	$184.48	3.292%	$190.5531	$190.55	$190.55	$190.60
Purchase #5	$199.53	8.448%	$216.3863	$216.39	$216.40	$216.40
Purchase #6	$25.77	9.282%	$28.162	$28.16	$28.15	$28.20
Purchase #7	$118.72	10.475%	$131.1559	$131.16	$131.15	$131.20
7 purchase totals =	$961.81		$1,026.1450	$1,026.15	$1,026.15	$1,026.20