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	$181.50	7.589%	$195.274	$195.27	$195.25	$195.30
Purchase #2	$222.36	11.292%	$247.4689	$247.47	$247.45	$247.50
Purchase #3	$116.88	8.418%	$126.719	$126.72	$126.70	$126.70
Purchase #4	$165.91	4.102%	$172.7156	$172.72	$172.70	$172.70
Purchase #5	$117.99	11.756%	$131.8609	$131.86	$131.85	$131.90
Purchase #6	$109.66	9.379%	$119.945	$119.95	$119.95	$119.90
Purchase #7	$247.29	13.345%	$280.2909	$280.29	$280.30	$280.30
7 purchase totals =	$1,161.59		$1,274.2743	$1,274.28	$1,274.20	$1,274.30