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	$183.54	10.684%	$203.1494	$203.15	$203.15	$203.10
Purchase #2	$158.75	10.821%	$175.9283	$175.93	$175.95	$175.90
Purchase #3	$177.25	9.698%	$194.4397	$194.44	$194.45	$194.40
Purchase #4	$70.83	10.764%	$78.4541	$78.45	$78.45	$78.50
Purchase #5	$99.66	11.664%	$111.2843	$111.28	$111.30	$111.30
Purchase #6	$132.91	11.467%	$148.1508	$148.15	$148.15	$148.20
Purchase #7	$5.56	10.438%	$6.1404	$6.14	$6.15	$6.10
7 purchase totals =	$828.50		$917.5470	$917.54	$917.60	$917.50