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	$12.59	11.300%	$14.0127	$14.01	$14.00	$14.00
Purchase #2	$83.70	6.344%	$89.0099	$89.01	$89.00	$89.00
Purchase #3	$181.89	12.314%	$204.2879	$204.29	$204.30	$204.30
Purchase #4	$126.32	11.827%	$141.2599	$141.26	$141.25	$141.30
Purchase #5	$200.43	13.189%	$226.8647	$226.86	$226.85	$226.90
Purchase #6	$219.91	5.353%	$231.6818	$231.68	$231.70	$231.70
Purchase #7	$17.50	5.462%	$18.4559	$18.46	$18.45	$18.50
7 purchase totals =	$842.34		$925.5728	$925.57	$925.55	$925.70