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	$219.27	12.535%	$246.7555	$246.76	$246.75	$246.80
Purchase #2	$132.67	13.501%	$150.5818	$150.58	$150.60	$150.60
Purchase #3	$18.87	13.686%	$21.4525	$21.45	$21.45	$21.50
Purchase #4	$40.68	7.325%	$43.6598	$43.66	$43.65	$43.70
Purchase #5	$184.83	11.603%	$206.2758	$206.28	$206.30	$206.30
Purchase #6	$228.88	12.109%	$256.5951	$256.60	$256.60	$256.60
Purchase #7	$236.52	10.658%	$261.7283	$261.73	$261.75	$261.70
7 purchase totals =	$1,061.72		$1,187.0488	$1,187.06	$1,187.10	$1,187.20