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	$214.93	3.355%	$222.1409	$222.14	$222.15	$222.10
Purchase #2	$109.45	13.721%	$124.4676	$124.47	$124.45	$124.50
Purchase #3	$51.70	7.783%	$55.7238	$55.72	$55.70	$55.70
Purchase #4	$138.39	6.115%	$146.8525	$146.85	$146.85	$146.90
Purchase #5	$110.30	13.288%	$124.9567	$124.96	$124.95	$125.00
Purchase #6	$13.83	5.546%	$14.597	$14.60	$14.60	$14.60
Purchase #7	$162.78	10.374%	$179.6668	$179.67	$179.65	$179.70
7 purchase totals =	$801.38		$868.4053	$868.41	$868.35	$868.50