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	$192.77	11.801%	$215.5188	$215.52	$215.50	$215.50
Purchase #2	$48.49	7.404%	$52.0802	$52.08	$52.10	$52.10
Purchase #3	$33.82	11.259%	$37.6278	$37.63	$37.65	$37.60
Purchase #4	$220.77	5.732%	$233.4245	$233.42	$233.40	$233.40
Purchase #5	$189.40	5.777%	$200.3416	$200.34	$200.35	$200.30
Purchase #6	$12.77	9.269%	$13.9537	$13.95	$13.95	$14.00
Purchase #7	$163.30	10.214%	$179.9795	$179.98	$180.00	$180.00
7 purchase totals =	$861.32		$932.9261	$932.92	$932.95	$932.90