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	$65.37	10.192%	$72.0325	$72.03	$72.05	$72.00
Purchase #2	$246.41	4.314%	$257.0401	$257.04	$257.05	$257.00
Purchase #3	$12.88	5.607%	$13.6022	$13.60	$13.60	$13.60
Purchase #4	$32.54	11.468%	$36.2717	$36.27	$36.25	$36.30
Purchase #5	$174.91	12.519%	$196.807	$196.81	$196.80	$196.80
Purchase #6	$226.40	6.761%	$241.7069	$241.71	$241.70	$241.70
Purchase #7	$109.37	4.810%	$114.6307	$114.63	$114.65	$114.60
7 purchase totals =	$867.88		$932.0911	$932.09	$932.10	$932.00