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	$240.86	9.147%	$262.8915	$262.89	$262.90	$262.90
Purchase #2	$127.54	7.626%	$137.2662	$137.27	$137.25	$137.30
Purchase #3	$108.76	9.593%	$119.1933	$119.19	$119.20	$119.20
Purchase #4	$75.76	6.787%	$80.9018	$80.90	$80.90	$80.90
Purchase #5	$55.72	11.182%	$61.9506	$61.95	$61.95	$62.00
Purchase #6	$92.72	7.775%	$99.929	$99.93	$99.95	$99.90
Purchase #7	$162.46	12.684%	$183.0664	$183.07	$183.05	$183.10
7 purchase totals =	$863.82		$945.1988	$945.20	$945.20	$945.30