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	$175.87	11.535%	$196.1566	$196.16	$196.15	$196.20
Purchase #2	$126.42	4.116%	$131.6234	$131.62	$131.60	$131.60
Purchase #3	$131.28	11.600%	$146.5085	$146.51	$146.50	$146.50
Purchase #4	$120.71	6.508%	$128.5658	$128.57	$128.55	$128.60
Purchase #5	$221.31	8.483%	$240.0837	$240.08	$240.10	$240.10
Purchase #6	$214.34	6.315%	$227.8756	$227.88	$227.90	$227.90
Purchase #7	$118.38	3.149%	$122.1078	$122.11	$122.10	$122.10
7 purchase totals =	$1,108.31		$1,192.9214	$1,192.93	$1,192.90	$1,193.00