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	$221.79	7.469%	$238.3555	$238.36	$238.35	$238.40
Purchase #2	$22.83	6.685%	$24.3562	$24.36	$24.35	$24.40
Purchase #3	$27.83	12.384%	$31.2765	$31.28	$31.30	$31.30
Purchase #4	$90.69	8.165%	$98.0948	$98.09	$98.10	$98.10
Purchase #5	$209.32	6.761%	$223.4721	$223.47	$223.45	$223.50
Purchase #6	$248.38	3.749%	$257.6918	$257.69	$257.70	$257.70
Purchase #7	$182.57	4.379%	$190.5647	$190.56	$190.55	$190.60
7 purchase totals =	$1,003.41		$1,063.8116	$1,063.81	$1,063.80	$1,064.00