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	$199.85	8.349%	$216.5355	$216.54	$216.55	$216.50
Purchase #2	$79.70	3.383%	$82.3963	$82.40	$82.40	$82.40
Purchase #3	$177.88	3.869%	$184.7622	$184.76	$184.75	$184.80
Purchase #4	$68.26	6.291%	$72.5542	$72.55	$72.55	$72.60
Purchase #5	$152.60	8.341%	$165.3284	$165.33	$165.35	$165.30
Purchase #6	$82.34	8.647%	$89.4599	$89.46	$89.45	$89.50
Purchase #7	$191.30	10.575%	$211.53	$211.53	$211.55	$211.50
7 purchase totals =	$951.93		$1,022.5665	$1,022.57	$1,022.60	$1,022.60