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	$148.61	9.452%	$162.6566	$162.66	$162.65	$162.70
Purchase #2	$59.48	10.451%	$65.6963	$65.70	$65.70	$65.70
Purchase #3	$113.27	12.454%	$127.3766	$127.38	$127.40	$127.40
Purchase #4	$177.48	10.242%	$195.6575	$195.66	$195.65	$195.70
Purchase #5	$90.96	10.637%	$100.6354	$100.64	$100.65	$100.60
Purchase #6	$160.94	4.247%	$167.7751	$167.78	$167.80	$167.80
Purchase #7	$145.60	7.645%	$156.7311	$156.73	$156.75	$156.70
7 purchase totals =	$896.34		$976.5286	$976.55	$976.60	$976.60