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	$96.50	8.439%	$104.6436	$104.64	$104.65	$104.60
Purchase #2	$42.73	8.783%	$46.483	$46.48	$46.50	$46.50
Purchase #3	$94.32	9.240%	$103.0352	$103.04	$103.05	$103.00
Purchase #4	$172.71	9.226%	$188.6442	$188.64	$188.65	$188.60
Purchase #5	$115.57	13.826%	$131.5487	$131.55	$131.55	$131.50
Purchase #6	$237.72	6.127%	$252.2851	$252.29	$252.30	$252.30
Purchase #7	$246.46	5.369%	$259.6924	$259.69	$259.70	$259.70
7 purchase totals =	$1,006.01		$1,086.3322	$1,086.33	$1,086.40	$1,086.20