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	$194.67	7.613%	$209.4902	$209.49	$209.50	$209.50
Purchase #2	$140.62	13.210%	$159.1959	$159.20	$159.20	$159.20
Purchase #3	$70.78	10.864%	$78.4695	$78.47	$78.45	$78.50
Purchase #4	$80.60	7.789%	$86.8779	$86.88	$86.90	$86.90
Purchase #5	$138.50	9.277%	$151.3486	$151.35	$151.35	$151.30
Purchase #6	$196.55	10.775%	$217.7283	$217.73	$217.75	$217.70
Purchase #7	$104.33	11.204%	$116.0191	$116.02	$116.00	$116.00
7 purchase totals =	$926.05		$1,019.1295	$1,019.14	$1,019.15	$1,019.10