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	$187.31	11.206%	$208.3	$208.30	$208.30	$208.30
Purchase #2	$80.67	6.148%	$85.6296	$85.63	$85.65	$85.60
Purchase #3	$208.42	9.845%	$228.9389	$228.94	$228.95	$228.90
Purchase #4	$243.51	13.203%	$275.6606	$275.66	$275.65	$275.70
Purchase #5	$97.89	5.620%	$103.3914	$103.39	$103.40	$103.40
Purchase #6	$50.57	4.115%	$52.651	$52.65	$52.65	$52.70
Purchase #7	$139.38	7.519%	$149.86	$149.86	$149.85	$149.90
7 purchase totals =	$1,007.75		$1,104.4315	$1,104.43	$1,104.45	$1,104.50