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	$233.28	12.415%	$262.2417	$262.24	$262.25	$262.20
Purchase #2	$195.94	6.735%	$209.1366	$209.14	$209.15	$209.10
Purchase #3	$43.81	5.710%	$46.3116	$46.31	$46.30	$46.30
Purchase #4	$146.88	6.520%	$156.4566	$156.46	$156.45	$156.50
Purchase #5	$107.89	3.712%	$111.8949	$111.89	$111.90	$111.90
Purchase #6	$116.66	12.345%	$131.0617	$131.06	$131.05	$131.10
Purchase #7	$101.58	3.711%	$105.3496	$105.35	$105.35	$105.30
7 purchase totals =	$946.04		$1,022.4527	$1,022.45	$1,022.45	$1,022.40