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	$88.33	8.179%	$95.5545	$95.55	$95.55	$95.60
Purchase #2	$12.79	5.494%	$13.4927	$13.49	$13.50	$13.50
Purchase #3	$169.62	5.780%	$179.424	$179.42	$179.40	$179.40
Purchase #4	$63.52	4.460%	$66.353	$66.35	$66.35	$66.40
Purchase #5	$59.53	9.604%	$65.2473	$65.25	$65.25	$65.20
Purchase #6	$32.29	3.646%	$33.4673	$33.47	$33.45	$33.50
Purchase #7	$163.54	12.652%	$184.2311	$184.23	$184.25	$184.20
7 purchase totals =	$589.62		$637.7699	$637.76	$637.75	$637.80