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	$9.59	7.529%	$10.312	$10.31	$10.30	$10.30
Purchase #2	$117.53	4.260%	$122.5368	$122.54	$122.55	$122.50
Purchase #3	$158.37	10.207%	$174.5348	$174.53	$174.55	$174.50
Purchase #4	$183.28	9.230%	$200.1967	$200.20	$200.20	$200.20
Purchase #5	$94.57	6.553%	$100.7672	$100.77	$100.75	$100.80
Purchase #6	$182.93	7.361%	$196.3955	$196.40	$196.40	$196.40
Purchase #7	$141.41	4.513%	$147.7918	$147.79	$147.80	$147.80
7 purchase totals =	$887.68		$952.5348	$952.54	$952.55	$952.50