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	$57.61	7.732%	$62.0644	$62.06	$62.05	$62.10
Purchase #2	$100.58	4.766%	$105.3736	$105.37	$105.35	$105.40
Purchase #3	$212.32	11.811%	$237.3971	$237.40	$237.40	$237.40
Purchase #4	$80.32	8.756%	$87.3528	$87.35	$87.35	$87.40
Purchase #5	$77.55	5.867%	$82.0999	$82.10	$82.10	$82.10
Purchase #6	$177.31	8.120%	$191.7076	$191.71	$191.70	$191.70
Purchase #7	$99.28	10.673%	$109.8762	$109.88	$109.90	$109.90
7 purchase totals =	$804.97		$875.8716	$875.87	$875.85	$876.00