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	$193.53	9.381%	$211.685	$211.69	$211.70	$211.70
Purchase #2	$82.71	7.730%	$89.1035	$89.10	$89.10	$89.10
Purchase #3	$141.29	13.697%	$160.6425	$160.64	$160.65	$160.60
Purchase #4	$143.33	9.342%	$156.7199	$156.72	$156.70	$156.70
Purchase #5	$225.97	4.307%	$235.7025	$235.70	$235.70	$235.70
Purchase #6	$132.90	13.449%	$150.7737	$150.77	$150.75	$150.80
Purchase #7	$82.60	13.832%	$94.0252	$94.03	$94.05	$94.00
7 purchase totals =	$1,002.33		$1,098.6523	$1,098.65	$1,098.65	$1,098.60