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	$130.25	13.686%	$148.076	$148.08	$148.10	$148.10
Purchase #2	$53.67	5.127%	$56.4217	$56.42	$56.40	$56.40
Purchase #3	$97.72	5.735%	$103.3242	$103.32	$103.30	$103.30
Purchase #4	$238.32	12.670%	$268.5151	$268.52	$268.50	$268.50
Purchase #5	$142.93	9.526%	$156.5455	$156.55	$156.55	$156.50
Purchase #6	$142.46	11.408%	$158.7118	$158.71	$158.70	$158.70
Purchase #7	$140.52	10.356%	$155.0723	$155.07	$155.05	$155.10
7 purchase totals =	$945.87		$1,046.6666	$1,046.67	$1,046.60	$1,046.60