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	$156.74	8.293%	$169.7384	$169.74	$169.75	$169.70
Purchase #2	$175.66	6.723%	$187.4696	$187.47	$187.45	$187.50
Purchase #3	$76.81	7.467%	$82.5454	$82.55	$82.55	$82.50
Purchase #4	$96.29	4.628%	$100.7463	$100.75	$100.75	$100.70
Purchase #5	$203.58	6.335%	$216.4768	$216.48	$216.50	$216.50
Purchase #6	$144.50	10.492%	$159.6609	$159.66	$159.65	$159.70
Purchase #7	$203.91	11.272%	$226.8947	$226.89	$226.90	$226.90
7 purchase totals =	$1,057.49		$1,143.5321	$1,143.54	$1,143.55	$1,143.50