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	$213.85	6.467%	$227.6797	$227.68	$227.70	$227.70
Purchase #2	$65.40	11.214%	$72.734	$72.73	$72.75	$72.70
Purchase #3	$168.89	9.795%	$185.4328	$185.43	$185.45	$185.40
Purchase #4	$76.75	11.493%	$85.5709	$85.57	$85.55	$85.60
Purchase #5	$168.54	10.511%	$186.2552	$186.26	$186.25	$186.30
Purchase #6	$167.38	13.318%	$189.6717	$189.67	$189.65	$189.70
Purchase #7	$90.79	7.664%	$97.7481	$97.75	$97.75	$97.70
7 purchase totals =	$951.60		$1,045.0924	$1,045.09	$1,045.10	$1,045.10