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	$134.95	9.795%	$148.1684	$148.17	$148.15	$148.20
Purchase #2	$120.34	8.413%	$130.4642	$130.46	$130.45	$130.50
Purchase #3	$124.57	4.529%	$130.2118	$130.21	$130.20	$130.20
Purchase #4	$111.49	10.811%	$123.5432	$123.54	$123.55	$123.50
Purchase #5	$241.92	6.629%	$257.9569	$257.96	$257.95	$258.00
Purchase #6	$36.46	11.208%	$40.5464	$40.55	$40.55	$40.50
Purchase #7	$229.77	4.662%	$240.4819	$240.48	$240.50	$240.50
7 purchase totals =	$999.50		$1,071.3728	$1,071.37	$1,071.35	$1,071.40