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	$215.98	8.359%	$234.0338	$234.03	$234.05	$234.00
Purchase #2	$208.72	5.314%	$219.8114	$219.81	$219.80	$219.80
Purchase #3	$199.57	12.169%	$223.8557	$223.86	$223.85	$223.90
Purchase #4	$74.31	5.854%	$78.6601	$78.66	$78.65	$78.70
Purchase #5	$96.38	3.111%	$99.3784	$99.38	$99.40	$99.40
Purchase #6	$21.81	6.783%	$23.2894	$23.29	$23.30	$23.30
Purchase #7	$161.49	3.566%	$167.2487	$167.25	$167.25	$167.20
7 purchase totals =	$978.26		$1,046.2775	$1,046.28	$1,046.30	$1,046.30