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	$194.25	10.134%	$213.9353	$213.94	$213.95	$213.90
Purchase #2	$68.48	13.254%	$77.5563	$77.56	$77.55	$77.60
Purchase #3	$20.81	3.341%	$21.5053	$21.51	$21.50	$21.50
Purchase #4	$67.63	6.326%	$71.9083	$71.91	$71.90	$71.90
Purchase #5	$97.61	11.530%	$108.8644	$108.86	$108.85	$108.90
Purchase #6	$88.45	6.221%	$93.9525	$93.95	$93.95	$94.00
Purchase #7	$101.48	11.183%	$112.8285	$112.83	$112.85	$112.80
7 purchase totals =	$638.71		$700.5506	$700.56	$700.55	$700.60