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	$66.78	10.337%	$73.683	$73.68	$73.70	$73.70
Purchase #2	$146.37	3.746%	$151.853	$151.85	$151.85	$151.90
Purchase #3	$51.38	4.300%	$53.5893	$53.59	$53.60	$53.60
Purchase #4	$209.87	6.123%	$222.7203	$222.72	$222.70	$222.70
Purchase #5	$81.30	8.371%	$88.1056	$88.11	$88.10	$88.10
Purchase #6	$178.58	5.327%	$188.093	$188.09	$188.10	$188.10
Purchase #7	$245.88	11.625%	$274.4636	$274.46	$274.45	$274.50
7 purchase totals =	$980.16		$1,052.5078	$1,052.50	$1,052.50	$1,052.60