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	$234.56	7.865%	$253.0081	$253.01	$253.00	$253.00
Purchase #2	$50.27	7.707%	$54.1443	$54.14	$54.15	$54.10
Purchase #3	$126.99	11.607%	$141.7297	$141.73	$141.75	$141.70
Purchase #4	$215.57	3.474%	$223.0589	$223.06	$223.05	$223.10
Purchase #5	$154.82	13.246%	$175.3275	$175.33	$175.35	$175.30
Purchase #6	$81.66	4.576%	$85.3968	$85.40	$85.40	$85.40
Purchase #7	$103.57	12.347%	$116.3578	$116.36	$116.35	$116.40
7 purchase totals =	$967.44		$1,049.0231	$1,049.03	$1,049.05	$1,049.00