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	$184.61	7.711%	$198.8453	$198.85	$198.85	$198.80
Purchase #2	$122.38	3.552%	$126.7269	$126.73	$126.75	$126.70
Purchase #3	$29.94	7.342%	$32.1382	$32.14	$32.15	$32.10
Purchase #4	$137.53	5.516%	$145.1162	$145.12	$145.10	$145.10
Purchase #5	$105.45	3.345%	$108.9773	$108.98	$109.00	$109.00
Purchase #6	$88.48	13.182%	$100.1434	$100.14	$100.15	$100.10
Purchase #7	$234.66	6.576%	$250.0912	$250.09	$250.10	$250.10
7 purchase totals =	$903.05		$962.0385	$962.05	$962.10	$961.90