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	$61.78	11.644%	$68.9737	$68.97	$68.95	$69.00
Purchase #2	$220.88	11.321%	$245.8858	$245.89	$245.90	$245.90
Purchase #3	$70.93	3.578%	$73.4679	$73.47	$73.45	$73.50
Purchase #4	$47.82	9.577%	$52.3997	$52.40	$52.40	$52.40
Purchase #5	$231.40	10.198%	$254.9982	$255.00	$255.00	$255.00
Purchase #6	$195.34	11.837%	$218.4624	$218.46	$218.45	$218.50
Purchase #7	$74.40	5.636%	$78.5932	$78.59	$78.60	$78.60
7 purchase totals =	$902.55		$992.7809	$992.78	$992.75	$992.90