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	$211.92	7.431%	$227.6678	$227.67	$227.65	$227.70
Purchase #2	$223.86	6.151%	$237.6296	$237.63	$237.65	$237.60
Purchase #3	$60.61	6.440%	$64.5133	$64.51	$64.50	$64.50
Purchase #4	$135.70	11.868%	$151.8049	$151.80	$151.80	$151.80
Purchase #5	$127.88	10.620%	$141.4609	$141.46	$141.45	$141.50
Purchase #6	$172.78	13.800%	$196.6236	$196.62	$196.60	$196.60
Purchase #7	$96.86	6.754%	$103.4019	$103.40	$103.40	$103.40
7 purchase totals =	$1,029.61		$1,123.1020	$1,123.09	$1,123.05	$1,123.10