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	$198.38	12.841%	$223.854	$223.85	$223.85	$223.90
Purchase #2	$9.39	11.626%	$10.4817	$10.48	$10.50	$10.50
Purchase #3	$50.75	11.478%	$56.5751	$56.58	$56.60	$56.60
Purchase #4	$183.63	3.298%	$189.6861	$189.69	$189.70	$189.70
Purchase #5	$56.90	10.501%	$62.8751	$62.88	$62.90	$62.90
Purchase #6	$211.43	12.128%	$237.0722	$237.07	$237.05	$237.10
Purchase #7	$223.56	10.824%	$247.7581	$247.76	$247.75	$247.80
7 purchase totals =	$934.04		$1,028.3023	$1,028.31	$1,028.35	$1,028.50