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	$242.56	8.108%	$262.2268	$262.23	$262.25	$262.20
Purchase #2	$139.68	8.667%	$151.7861	$151.79	$151.80	$151.80
Purchase #3	$116.68	6.621%	$124.4054	$124.41	$124.40	$124.40
Purchase #4	$95.36	4.715%	$99.8562	$99.86	$99.85	$99.90
Purchase #5	$178.85	6.421%	$190.334	$190.33	$190.35	$190.30
Purchase #6	$117.59	12.485%	$132.2711	$132.27	$132.25	$132.30
Purchase #7	$218.62	11.529%	$243.8247	$243.82	$243.80	$243.80
7 purchase totals =	$1,109.34		$1,204.7043	$1,204.71	$1,204.70	$1,204.70