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	$108.56	10.414%	$119.8654	$119.87	$119.85	$119.90
Purchase #2	$162.27	13.447%	$184.0904	$184.09	$184.10	$184.10
Purchase #3	$16.75	12.591%	$18.859	$18.86	$18.85	$18.90
Purchase #4	$57.37	7.534%	$61.6923	$61.69	$61.70	$61.70
Purchase #5	$95.94	13.270%	$108.6712	$108.67	$108.65	$108.70
Purchase #6	$99.93	9.626%	$109.5493	$109.55	$109.55	$109.50
Purchase #7	$21.75	3.105%	$22.4253	$22.43	$22.45	$22.40
7 purchase totals =	$562.57		$625.1529	$625.16	$625.15	$625.20