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	$146.26	7.291%	$156.9238	$156.92	$156.90	$156.90
Purchase #2	$150.69	12.404%	$169.3816	$169.38	$169.40	$169.40
Purchase #3	$102.85	8.716%	$111.8144	$111.81	$111.80	$111.80
Purchase #4	$150.25	11.506%	$167.5378	$167.54	$167.55	$167.50
Purchase #5	$215.63	10.272%	$237.7795	$237.78	$237.80	$237.80
Purchase #6	$144.46	5.826%	$152.8762	$152.88	$152.90	$152.90
Purchase #7	$55.70	11.736%	$62.237	$62.24	$62.25	$62.20
7 purchase totals =	$965.84		$1,058.5503	$1,058.55	$1,058.60	$1,058.50