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	$197.46	10.245%	$217.6898	$217.69	$217.70	$217.70
Purchase #2	$99.71	12.324%	$111.9983	$112.00	$112.00	$112.00
Purchase #3	$187.36	4.851%	$196.4488	$196.45	$196.45	$196.40
Purchase #4	$40.32	5.183%	$42.4098	$42.41	$42.40	$42.40
Purchase #5	$139.47	3.836%	$144.8201	$144.82	$144.80	$144.80
Purchase #6	$200.80	11.563%	$224.0185	$224.02	$224.00	$224.00
Purchase #7	$166.45	13.799%	$189.4184	$189.42	$189.40	$189.40
7 purchase totals =	$1,031.57		$1,126.8037	$1,126.81	$1,126.75	$1,126.70