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	$188.90	5.523%	$199.3329	$199.33	$199.35	$199.30
Purchase #2	$27.28	6.558%	$29.069	$29.07	$29.05	$29.10
Purchase #3	$154.27	4.600%	$161.3664	$161.37	$161.35	$161.40
Purchase #4	$80.96	5.638%	$85.5245	$85.52	$85.50	$85.50
Purchase #5	$189.51	12.562%	$213.3162	$213.32	$213.30	$213.30
Purchase #6	$139.69	11.714%	$156.0533	$156.05	$156.05	$156.10
Purchase #7	$198.56	6.573%	$211.6113	$211.61	$211.60	$211.60
7 purchase totals =	$979.17		$1,056.2736	$1,056.27	$1,056.20	$1,056.30