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	$160.87	8.637%	$174.7643	$174.76	$174.75	$174.80
Purchase #2	$27.59	7.361%	$29.6209	$29.62	$29.60	$29.60
Purchase #3	$71.48	9.495%	$78.267	$78.27	$78.25	$78.30
Purchase #4	$163.80	5.259%	$172.4142	$172.41	$172.40	$172.40
Purchase #5	$136.76	5.269%	$143.9659	$143.97	$143.95	$144.00
Purchase #6	$172.71	3.368%	$178.5269	$178.53	$178.55	$178.50
Purchase #7	$169.72	9.451%	$185.7602	$185.76	$185.75	$185.80
7 purchase totals =	$902.93		$963.3194	$963.32	$963.25	$963.40