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	$217.27	5.139%	$228.4355	$228.44	$228.45	$228.40
Purchase #2	$32.66	5.740%	$34.5347	$34.53	$34.55	$34.50
Purchase #3	$104.39	8.314%	$113.069	$113.07	$113.05	$113.10
Purchase #4	$165.82	5.584%	$175.0794	$175.08	$175.10	$175.10
Purchase #5	$128.90	11.326%	$143.4992	$143.50	$143.50	$143.50
Purchase #6	$46.26	3.195%	$47.738	$47.74	$47.75	$47.70
Purchase #7	$127.71	11.861%	$142.8577	$142.86	$142.85	$142.90
7 purchase totals =	$823.01		$885.2135	$885.22	$885.25	$885.20