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	$161.61	5.140%	$169.9168	$169.92	$169.90	$169.90
Purchase #2	$167.42	13.178%	$189.4826	$189.48	$189.50	$189.50
Purchase #3	$149.85	4.637%	$156.7985	$156.80	$156.80	$156.80
Purchase #4	$38.77	7.528%	$41.6886	$41.69	$41.70	$41.70
Purchase #5	$155.59	9.790%	$170.8223	$170.82	$170.80	$170.80
Purchase #6	$18.92	5.393%	$19.9404	$19.94	$19.95	$19.90
Purchase #7	$243.57	11.104%	$270.616	$270.62	$270.60	$270.60
7 purchase totals =	$935.73		$1,019.2652	$1,019.27	$1,019.25	$1,019.20