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	$200.82	4.595%	$210.0477	$210.05	$210.05	$210.00
Purchase #2	$217.90	12.844%	$245.8871	$245.89	$245.90	$245.90
Purchase #3	$59.93	10.759%	$66.3779	$66.38	$66.40	$66.40
Purchase #4	$7.80	5.854%	$8.2566	$8.26	$8.25	$8.30
Purchase #5	$185.63	12.609%	$209.0361	$209.04	$209.05	$209.00
Purchase #6	$107.92	6.286%	$114.7039	$114.70	$114.70	$114.70
Purchase #7	$145.56	11.714%	$162.6109	$162.61	$162.60	$162.60
7 purchase totals =	$925.56		$1,016.9202	$1,016.93	$1,016.95	$1,016.90