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	$56.85	10.524%	$62.8329	$62.83	$62.85	$62.80
Purchase #2	$43.86	11.501%	$48.9043	$48.90	$48.90	$48.90
Purchase #3	$209.63	5.121%	$220.3652	$220.37	$220.35	$220.40
Purchase #4	$211.59	7.628%	$227.7301	$227.73	$227.75	$227.70
Purchase #5	$102.57	11.416%	$114.2794	$114.28	$114.30	$114.30
Purchase #6	$116.84	11.720%	$130.5336	$130.53	$130.55	$130.50
Purchase #7	$195.67	8.311%	$211.9321	$211.93	$211.95	$211.90
7 purchase totals =	$937.01		$1,016.5776	$1,016.57	$1,016.65	$1,016.50