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	$174.75	9.523%	$191.3914	$191.39	$191.40	$191.40
Purchase #2	$32.81	4.424%	$34.2615	$34.26	$34.25	$34.30
Purchase #3	$99.25	5.139%	$104.3505	$104.35	$104.35	$104.40
Purchase #4	$212.32	6.356%	$225.8151	$225.82	$225.80	$225.80
Purchase #5	$103.80	10.321%	$114.5132	$114.51	$114.50	$114.50
Purchase #6	$187.68	11.653%	$209.5504	$209.55	$209.55	$209.60
Purchase #7	$120.67	13.430%	$136.876	$136.88	$136.90	$136.90
7 purchase totals =	$931.28		$1,016.7581	$1,016.76	$1,016.75	$1,016.90