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	$43.51	4.817%	$45.6059	$45.61	$45.60	$45.60
Purchase #2	$10.59	4.487%	$11.0652	$11.07	$11.05	$11.10
Purchase #3	$20.61	4.561%	$21.55	$21.55	$21.55	$21.60
Purchase #4	$69.46	6.108%	$73.7026	$73.70	$73.70	$73.70
Purchase #5	$226.61	4.488%	$236.7803	$236.78	$236.80	$236.80
Purchase #6	$209.60	11.597%	$233.9073	$233.91	$233.90	$233.90
Purchase #7	$37.71	5.718%	$39.8663	$39.87	$39.85	$39.90
7 purchase totals =	$618.09		$662.4776	$662.49	$662.45	$662.60