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	$197.76	11.481%	$220.4648	$220.46	$220.45	$220.50
Purchase #2	$16.95	3.350%	$17.5178	$17.52	$17.50	$17.50
Purchase #3	$245.40	9.589%	$268.9314	$268.93	$268.95	$268.90
Purchase #4	$200.46	5.792%	$212.0706	$212.07	$212.05	$212.10
Purchase #5	$80.34	6.685%	$85.7107	$85.71	$85.70	$85.70
Purchase #6	$94.85	11.272%	$105.5415	$105.54	$105.55	$105.50
Purchase #7	$164.95	12.500%	$185.5688	$185.57	$185.55	$185.60
7 purchase totals =	$1,000.71		$1,095.8056	$1,095.80	$1,095.75	$1,095.80