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	$215.88	13.808%	$245.6887	$245.69	$245.70	$245.70
Purchase #2	$29.36	8.813%	$31.9475	$31.95	$31.95	$31.90
Purchase #3	$109.81	4.278%	$114.5077	$114.51	$114.50	$114.50
Purchase #4	$219.39	10.574%	$242.5883	$242.59	$242.60	$242.60
Purchase #5	$176.35	3.139%	$181.8856	$181.89	$181.90	$181.90
Purchase #6	$29.48	3.825%	$30.6076	$30.61	$30.60	$30.60
Purchase #7	$209.45	3.140%	$216.0267	$216.03	$216.05	$216.00
7 purchase totals =	$989.72		$1,063.2521	$1,063.27	$1,063.30	$1,063.20