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	$181.34	7.461%	$194.8698	$194.87	$194.85	$194.90
Purchase #2	$46.48	9.861%	$51.0634	$51.06	$51.05	$51.10
Purchase #3	$128.73	11.191%	$143.1362	$143.14	$143.15	$143.10
Purchase #4	$11.87	8.263%	$12.8508	$12.85	$12.85	$12.90
Purchase #5	$168.81	13.449%	$191.5133	$191.51	$191.50	$191.50
Purchase #6	$94.62	6.637%	$100.8999	$100.90	$100.90	$100.90
Purchase #7	$51.46	12.212%	$57.7443	$57.74	$57.75	$57.70
7 purchase totals =	$683.31		$752.0777	$752.07	$752.05	$752.10