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	$224.72	10.338%	$247.9516	$247.95	$247.95	$248.00
Purchase #2	$67.35	6.109%	$71.4644	$71.46	$71.45	$71.50
Purchase #3	$40.83	13.123%	$46.1881	$46.19	$46.20	$46.20
Purchase #4	$136.74	6.373%	$145.4544	$145.45	$145.45	$145.50
Purchase #5	$223.80	6.772%	$238.9557	$238.96	$238.95	$239.00
Purchase #6	$93.37	10.803%	$103.4568	$103.46	$103.45	$103.50
Purchase #7	$176.27	9.835%	$193.6062	$193.61	$193.60	$193.60
7 purchase totals =	$963.08		$1,047.0772	$1,047.08	$1,047.05	$1,047.30