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	$128.53	9.372%	$140.5758	$140.58	$140.60	$140.60
Purchase #2	$191.52	9.192%	$209.1245	$209.12	$209.10	$209.10
Purchase #3	$57.94	5.444%	$61.0943	$61.09	$61.10	$61.10
Purchase #4	$188.52	8.485%	$204.5159	$204.52	$204.50	$204.50
Purchase #5	$80.78	10.827%	$89.5261	$89.53	$89.55	$89.50
Purchase #6	$173.68	5.439%	$183.1265	$183.13	$183.15	$183.10
Purchase #7	$149.72	5.274%	$157.6162	$157.62	$157.60	$157.60
7 purchase totals =	$970.69		$1,045.5793	$1,045.59	$1,045.60	$1,045.50