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	$162.45	4.436%	$169.6563	$169.66	$169.65	$169.70
Purchase #2	$80.85	3.786%	$83.911	$83.91	$83.90	$83.90
Purchase #3	$33.82	11.143%	$37.5886	$37.59	$37.60	$37.60
Purchase #4	$151.31	3.650%	$156.8328	$156.83	$156.85	$156.80
Purchase #5	$71.80	6.829%	$76.7032	$76.70	$76.70	$76.70
Purchase #6	$132.45	7.171%	$141.948	$141.95	$141.95	$141.90
Purchase #7	$213.92	7.453%	$229.8635	$229.86	$229.85	$229.90
7 purchase totals =	$846.60		$896.5034	$896.50	$896.50	$896.50