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	$119.71	5.855%	$126.719	$126.72	$126.70	$126.70
Purchase #2	$103.52	5.169%	$108.8709	$108.87	$108.85	$108.90
Purchase #3	$193.69	3.693%	$200.843	$200.84	$200.85	$200.80
Purchase #4	$232.72	3.511%	$240.8908	$240.89	$240.90	$240.90
Purchase #5	$143.55	13.210%	$162.513	$162.51	$162.50	$162.50
Purchase #6	$129.55	10.511%	$143.167	$143.17	$143.15	$143.20
Purchase #7	$234.27	3.691%	$242.9169	$242.92	$242.90	$242.90
7 purchase totals =	$1,157.01		$1,225.9206	$1,225.92	$1,225.85	$1,225.90