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	$141.28	13.494%	$160.3443	$160.34	$160.35	$160.30
Purchase #2	$106.44	9.689%	$116.753	$116.75	$116.75	$116.80
Purchase #3	$22.83	7.796%	$24.6098	$24.61	$24.60	$24.60
Purchase #4	$76.43	8.385%	$82.8387	$82.84	$82.85	$82.80
Purchase #5	$249.43	12.462%	$280.514	$280.51	$280.50	$280.50
Purchase #6	$242.86	11.813%	$271.5491	$271.55	$271.55	$271.50
Purchase #7	$112.26	3.773%	$116.4956	$116.50	$116.50	$116.50
7 purchase totals =	$951.53		$1,053.1045	$1,053.10	$1,053.10	$1,053.00