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	$210.62	11.435%	$234.7044	$234.70	$234.70	$234.70
Purchase #2	$107.30	9.444%	$117.4334	$117.43	$117.45	$117.40
Purchase #3	$53.75	11.425%	$59.8909	$59.89	$59.90	$59.90
Purchase #4	$94.85	8.365%	$102.7842	$102.78	$102.80	$102.80
Purchase #5	$102.86	13.602%	$116.851	$116.85	$116.85	$116.90
Purchase #6	$196.82	7.507%	$211.5953	$211.60	$211.60	$211.60
Purchase #7	$201.99	9.853%	$221.8921	$221.89	$221.90	$221.90
7 purchase totals =	$968.19		$1,065.1513	$1,065.14	$1,065.20	$1,065.20