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	$215.77	10.590%	$238.62	$238.62	$238.60	$238.60
Purchase #2	$27.66	12.684%	$31.1684	$31.17	$31.15	$31.20
Purchase #3	$203.38	4.505%	$212.5423	$212.54	$212.55	$212.50
Purchase #4	$93.70	10.257%	$103.3108	$103.31	$103.30	$103.30
Purchase #5	$166.30	11.208%	$184.9389	$184.94	$184.95	$184.90
Purchase #6	$107.29	6.340%	$114.0922	$114.09	$114.10	$114.10
Purchase #7	$166.71	7.155%	$178.6381	$178.64	$178.65	$178.60
7 purchase totals =	$980.81		$1,063.3107	$1,063.31	$1,063.30	$1,063.20