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	$209.26	6.498%	$222.8577	$222.86	$222.85	$222.90
Purchase #2	$6.71	11.729%	$7.497	$7.50	$7.50	$7.50
Purchase #3	$69.57	11.696%	$77.7069	$77.71	$77.70	$77.70
Purchase #4	$228.50	7.549%	$245.7495	$245.75	$245.75	$245.70
Purchase #5	$198.80	11.178%	$221.0219	$221.02	$221.00	$221.00
Purchase #6	$124.91	13.460%	$141.7229	$141.72	$141.70	$141.70
Purchase #7	$151.43	9.262%	$165.4554	$165.46	$165.45	$165.50
7 purchase totals =	$989.18		$1,082.0113	$1,082.02	$1,081.95	$1,082.00