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	$184.82	7.179%	$198.0882	$198.09	$198.10	$198.10
Purchase #2	$141.46	6.405%	$150.5205	$150.52	$150.50	$150.50
Purchase #3	$23.38	4.206%	$24.3634	$24.36	$24.35	$24.40
Purchase #4	$55.85	3.341%	$57.7159	$57.72	$57.70	$57.70
Purchase #5	$191.52	12.472%	$215.4064	$215.41	$215.40	$215.40
Purchase #6	$185.68	7.419%	$199.4556	$199.46	$199.45	$199.50
Purchase #7	$229.90	11.346%	$255.9845	$255.98	$256.00	$256.00
7 purchase totals =	$1,012.61		$1,101.5345	$1,101.54	$1,101.50	$1,101.60