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	$191.43	9.641%	$209.8858	$209.89	$209.90	$209.90
Purchase #2	$81.40	8.682%	$88.4671	$88.47	$88.45	$88.50
Purchase #3	$244.33	4.789%	$256.031	$256.03	$256.05	$256.00
Purchase #4	$67.72	7.130%	$72.5484	$72.55	$72.55	$72.50
Purchase #5	$231.92	10.841%	$257.0624	$257.06	$257.05	$257.10
Purchase #6	$152.70	5.412%	$160.9641	$160.96	$160.95	$161.00
Purchase #7	$25.93	13.536%	$29.4399	$29.44	$29.45	$29.40
7 purchase totals =	$995.43		$1,074.3987	$1,074.40	$1,074.40	$1,074.40