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	$190.76	10.758%	$211.282	$211.28	$211.30	$211.30
Purchase #2	$196.65	8.868%	$214.0889	$214.09	$214.10	$214.10
Purchase #3	$146.56	12.651%	$165.1013	$165.10	$165.10	$165.10
Purchase #4	$185.80	5.771%	$196.5225	$196.52	$196.50	$196.50
Purchase #5	$99.46	10.471%	$109.8745	$109.87	$109.85	$109.90
Purchase #6	$188.25	6.373%	$200.2472	$200.25	$200.25	$200.20
Purchase #7	$123.57	4.267%	$128.8427	$128.84	$128.85	$128.80
7 purchase totals =	$1,131.05		$1,225.9591	$1,225.95	$1,225.95	$1,225.90