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	$144.92	12.245%	$162.6655	$162.67	$162.65	$162.70
Purchase #2	$11.69	13.567%	$13.276	$13.28	$13.30	$13.30
Purchase #3	$162.71	13.430%	$184.562	$184.56	$184.55	$184.60
Purchase #4	$116.46	13.596%	$132.2939	$132.29	$132.30	$132.30
Purchase #5	$68.71	4.346%	$71.6961	$71.70	$71.70	$71.70
Purchase #6	$136.26	10.142%	$150.0795	$150.08	$150.10	$150.10
Purchase #7	$55.82	7.141%	$59.8061	$59.81	$59.80	$59.80
7 purchase totals =	$696.57		$774.3791	$774.39	$774.40	$774.50