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	$108.27	7.817%	$116.7335	$116.73	$116.75	$116.70
Purchase #2	$234.46	9.359%	$256.4031	$256.40	$256.40	$256.40
Purchase #3	$221.76	8.821%	$241.3214	$241.32	$241.30	$241.30
Purchase #4	$24.93	12.474%	$28.0398	$28.04	$28.05	$28.00
Purchase #5	$96.48	4.285%	$100.6142	$100.61	$100.60	$100.60
Purchase #6	$188.96	3.244%	$195.0899	$195.09	$195.10	$195.10
Purchase #7	$70.96	7.564%	$76.3274	$76.33	$76.35	$76.30
7 purchase totals =	$945.82		$1,014.5293	$1,014.52	$1,014.55	$1,014.40