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	$237.57	5.209%	$249.945	$249.95	$249.95	$249.90
Purchase #2	$49.44	6.312%	$52.5607	$52.56	$52.55	$52.60
Purchase #3	$246.77	13.850%	$280.9476	$280.95	$280.95	$280.90
Purchase #4	$173.64	5.339%	$182.9106	$182.91	$182.90	$182.90
Purchase #5	$134.28	12.574%	$151.1644	$151.16	$151.15	$151.20
Purchase #6	$109.37	6.313%	$116.2745	$116.27	$116.25	$116.30
Purchase #7	$12.86	12.763%	$14.5013	$14.50	$14.50	$14.50
7 purchase totals =	$963.93		$1,048.3041	$1,048.30	$1,048.25	$1,048.30