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	$190.46	3.405%	$196.9452	$196.95	$196.95	$196.90
Purchase #2	$247.95	6.648%	$264.4337	$264.43	$264.45	$264.40
Purchase #3	$62.89	5.776%	$66.5225	$66.52	$66.50	$66.50
Purchase #4	$118.59	11.374%	$132.0784	$132.08	$132.10	$132.10
Purchase #5	$126.80	10.715%	$140.3866	$140.39	$140.40	$140.40
Purchase #6	$184.88	3.150%	$190.7037	$190.70	$190.70	$190.70
Purchase #7	$52.27	7.408%	$56.1422	$56.14	$56.15	$56.10
7 purchase totals =	$983.84		$1,047.2123	$1,047.21	$1,047.25	$1,047.10