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	$152.38	4.660%	$159.4809	$159.48	$159.50	$159.50
Purchase #2	$170.69	6.351%	$181.5305	$181.53	$181.55	$181.50
Purchase #3	$118.59	11.333%	$132.0298	$132.03	$132.05	$132.00
Purchase #4	$24.89	13.295%	$28.1991	$28.20	$28.20	$28.20
Purchase #5	$102.85	8.862%	$111.9646	$111.96	$111.95	$112.00
Purchase #6	$232.69	4.457%	$243.061	$243.06	$243.05	$243.10
Purchase #7	$143.58	7.447%	$154.2724	$154.27	$154.25	$154.30
7 purchase totals =	$945.67		$1,010.5383	$1,010.53	$1,010.55	$1,010.60