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	$132.51	11.479%	$147.7208	$147.72	$147.70	$147.70
Purchase #2	$21.83	11.650%	$24.3732	$24.37	$24.35	$24.40
Purchase #3	$99.27	12.725%	$111.9021	$111.90	$111.90	$111.90
Purchase #4	$171.45	7.585%	$184.4545	$184.45	$184.45	$184.50
Purchase #5	$125.94	6.388%	$133.985	$133.99	$134.00	$134.00
Purchase #6	$105.41	8.156%	$114.0072	$114.01	$114.00	$114.00
Purchase #7	$117.72	11.574%	$131.3449	$131.34	$131.35	$131.30
7 purchase totals =	$774.13		$847.7877	$847.78	$847.75	$847.80