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	$198.96	3.207%	$205.3406	$205.34	$205.35	$205.30
Purchase #2	$16.78	12.429%	$18.8656	$18.87	$18.85	$18.90
Purchase #3	$54.51	5.655%	$57.5925	$57.59	$57.60	$57.60
Purchase #4	$145.90	4.834%	$152.9528	$152.95	$152.95	$153.00
Purchase #5	$196.76	11.650%	$219.6825	$219.68	$219.70	$219.70
Purchase #6	$213.82	7.175%	$229.1616	$229.16	$229.15	$229.20
Purchase #7	$208.85	12.468%	$234.8894	$234.89	$234.90	$234.90
7 purchase totals =	$1,035.58		$1,118.4850	$1,118.48	$1,118.50	$1,118.60