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	$88.89	11.553%	$99.1595	$99.16	$99.15	$99.20
Purchase #2	$6.94	3.860%	$7.2079	$7.21	$7.20	$7.20
Purchase #3	$44.26	13.773%	$50.3559	$50.36	$50.35	$50.40
Purchase #4	$139.89	13.702%	$159.0577	$159.06	$159.05	$159.10
Purchase #5	$133.80	13.577%	$151.966	$151.97	$151.95	$152.00
Purchase #6	$190.90	9.684%	$209.3868	$209.39	$209.40	$209.40
Purchase #7	$247.89	10.591%	$274.144	$274.14	$274.15	$274.10
7 purchase totals =	$852.57		$951.2778	$951.29	$951.25	$951.40