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	$146.53	11.191%	$162.9282	$162.93	$162.95	$162.90
Purchase #2	$116.50	9.410%	$127.4627	$127.46	$127.45	$127.50
Purchase #3	$47.74	9.354%	$52.2056	$52.21	$52.20	$52.20
Purchase #4	$83.34	3.237%	$86.0377	$86.04	$86.05	$86.00
Purchase #5	$58.83	13.485%	$66.7632	$66.76	$66.75	$66.80
Purchase #6	$169.79	5.396%	$178.9519	$178.95	$178.95	$179.00
Purchase #7	$211.90	5.478%	$223.5079	$223.51	$223.50	$223.50
7 purchase totals =	$834.63		$897.8572	$897.86	$897.85	$897.90