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	$215.37	10.644%	$238.294	$238.29	$238.30	$238.30
Purchase #2	$141.88	7.813%	$152.9651	$152.97	$152.95	$153.00
Purchase #3	$33.32	3.291%	$34.4166	$34.42	$34.40	$34.40
Purchase #4	$192.57	3.544%	$199.3947	$199.39	$199.40	$199.40
Purchase #5	$43.59	6.584%	$46.46	$46.46	$46.45	$46.50
Purchase #6	$164.87	5.188%	$173.4235	$173.42	$173.40	$173.40
Purchase #7	$156.37	6.725%	$166.8859	$166.89	$166.90	$166.90
7 purchase totals =	$947.97		$1,011.8398	$1,011.84	$1,011.80	$1,011.90