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	$188.31	4.524%	$196.8291	$196.83	$196.85	$196.80
Purchase #2	$60.86	4.302%	$63.4782	$63.48	$63.50	$63.50
Purchase #3	$216.38	13.268%	$245.0893	$245.09	$245.10	$245.10
Purchase #4	$241.60	5.836%	$255.6998	$255.70	$255.70	$255.70
Purchase #5	$223.97	7.447%	$240.649	$240.65	$240.65	$240.60
Purchase #6	$111.85	7.854%	$120.6347	$120.63	$120.65	$120.60
Purchase #7	$59.57	4.171%	$62.0547	$62.05	$62.05	$62.10
7 purchase totals =	$1,102.54		$1,184.4348	$1,184.43	$1,184.50	$1,184.40