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	$196.73	9.282%	$214.9905	$214.99	$215.00	$215.00
Purchase #2	$66.42	3.816%	$68.9546	$68.95	$68.95	$69.00
Purchase #3	$94.31	7.434%	$101.321	$101.32	$101.30	$101.30
Purchase #4	$178.71	5.692%	$188.8822	$188.88	$188.90	$188.90
Purchase #5	$230.54	5.597%	$243.4433	$243.44	$243.45	$243.40
Purchase #6	$42.40	8.225%	$45.8874	$45.89	$45.90	$45.90
Purchase #7	$169.47	7.698%	$182.5158	$182.52	$182.50	$182.50
7 purchase totals =	$978.58		$1,045.9948	$1,045.99	$1,046.00	$1,046.00