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	$153.77	11.663%	$171.7042	$171.70	$171.70	$171.70
Purchase #2	$230.81	7.304%	$247.6684	$247.67	$247.65	$247.70
Purchase #3	$18.63	13.347%	$21.1165	$21.12	$21.10	$21.10
Purchase #4	$91.37	13.189%	$103.4208	$103.42	$103.40	$103.40
Purchase #5	$180.31	4.143%	$187.7802	$187.78	$187.80	$187.80
Purchase #6	$176.53	11.397%	$196.6491	$196.65	$196.65	$196.60
Purchase #7	$237.49	7.190%	$254.5655	$254.57	$254.55	$254.60
7 purchase totals =	$1,088.91		$1,182.9047	$1,182.91	$1,182.85	$1,182.90