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	$153.96	5.192%	$161.9536	$161.95	$161.95	$162.00
Purchase #2	$34.39	8.604%	$37.3489	$37.35	$37.35	$37.30
Purchase #3	$207.42	10.268%	$228.7179	$228.72	$228.70	$228.70
Purchase #4	$35.70	9.110%	$38.9523	$38.95	$38.95	$39.00
Purchase #5	$228.96	11.525%	$255.3476	$255.35	$255.35	$255.30
Purchase #6	$50.48	4.188%	$52.5941	$52.59	$52.60	$52.60
Purchase #7	$220.61	5.767%	$233.3326	$233.33	$233.35	$233.30
7 purchase totals =	$931.52		$1,008.2470	$1,008.24	$1,008.25	$1,008.20