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	$56.86	10.320%	$62.728	$62.73	$62.75	$62.70
Purchase #2	$156.45	8.377%	$169.5558	$169.56	$169.55	$169.60
Purchase #3	$246.95	5.140%	$259.6432	$259.64	$259.65	$259.60
Purchase #4	$238.88	12.868%	$269.6191	$269.62	$269.60	$269.60
Purchase #5	$31.32	6.870%	$33.4717	$33.47	$33.45	$33.50
Purchase #6	$205.57	13.352%	$233.0177	$233.02	$233.00	$233.00
Purchase #7	$108.29	7.699%	$116.6272	$116.63	$116.65	$116.60
7 purchase totals =	$1,044.32		$1,144.6627	$1,144.67	$1,144.65	$1,144.60