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	$48.89	6.208%	$51.9251	$51.93	$51.95	$51.90
Purchase #2	$60.65	6.849%	$64.8039	$64.80	$64.80	$64.80
Purchase #3	$91.54	13.677%	$104.0599	$104.06	$104.05	$104.10
Purchase #4	$84.72	5.390%	$89.2864	$89.29	$89.30	$89.30
Purchase #5	$209.68	5.430%	$221.0656	$221.07	$221.05	$221.10
Purchase #6	$245.90	3.268%	$253.936	$253.94	$253.95	$253.90
Purchase #7	$243.29	7.391%	$261.2716	$261.27	$261.25	$261.30
7 purchase totals =	$984.67		$1,046.3485	$1,046.36	$1,046.35	$1,046.40