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	$152.45	6.809%	$162.8303	$162.83	$162.85	$162.80
Purchase #2	$152.56	6.441%	$162.3864	$162.39	$162.40	$162.40
Purchase #3	$41.32	5.444%	$43.5695	$43.57	$43.55	$43.60
Purchase #4	$47.91	10.744%	$53.0575	$53.06	$53.05	$53.10
Purchase #5	$59.90	4.248%	$62.4446	$62.44	$62.45	$62.40
Purchase #6	$39.46	11.609%	$44.0409	$44.04	$44.05	$44.00
Purchase #7	$112.48	10.709%	$124.5255	$124.53	$124.55	$124.50
7 purchase totals =	$606.08		$652.8547	$652.86	$652.90	$652.80