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	$85.93	13.103%	$97.1894	$97.19	$97.20	$97.20
Purchase #2	$98.54	13.832%	$112.1701	$112.17	$112.15	$112.20
Purchase #3	$154.39	7.771%	$166.3876	$166.39	$166.40	$166.40
Purchase #4	$211.38	6.728%	$225.6016	$225.60	$225.60	$225.60
Purchase #5	$168.78	11.396%	$188.0142	$188.01	$188.00	$188.00
Purchase #6	$200.26	6.596%	$213.4691	$213.47	$213.45	$213.50
Purchase #7	$47.89	12.175%	$53.7206	$53.72	$53.70	$53.70
7 purchase totals =	$967.17		$1,056.5526	$1,056.55	$1,056.50	$1,056.60