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	$162.85	7.741%	$175.4562	$175.46	$175.45	$175.50
Purchase #2	$245.46	4.237%	$255.8601	$255.86	$255.85	$255.90
Purchase #3	$138.55	7.678%	$149.1879	$149.19	$149.20	$149.20
Purchase #4	$201.96	6.474%	$215.0349	$215.03	$215.05	$215.00
Purchase #5	$5.47	8.500%	$5.935	$5.94	$5.95	$5.90
Purchase #6	$69.37	4.593%	$72.5562	$72.56	$72.55	$72.60
Purchase #7	$162.63	3.848%	$168.888	$168.89	$168.90	$168.90
7 purchase totals =	$986.29		$1,042.9183	$1,042.93	$1,042.95	$1,043.00