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	$154.79	9.433%	$169.3913	$169.39	$169.40	$169.40
Purchase #2	$152.41	4.642%	$159.4849	$159.48	$159.50	$159.50
Purchase #3	$42.87	10.532%	$47.3851	$47.39	$47.40	$47.40
Purchase #4	$48.46	6.223%	$51.4757	$51.48	$51.50	$51.50
Purchase #5	$215.43	3.648%	$223.2889	$223.29	$223.30	$223.30
Purchase #6	$219.29	5.207%	$230.7084	$230.71	$230.70	$230.70
Purchase #7	$73.51	12.417%	$82.6377	$82.64	$82.65	$82.60
7 purchase totals =	$906.76		$964.3720	$964.38	$964.45	$964.40