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	$185.49	11.523%	$206.864	$206.86	$206.85	$206.90
Purchase #2	$227.62	13.588%	$258.549	$258.55	$258.55	$258.50
Purchase #3	$78.55	9.506%	$86.017	$86.02	$86.00	$86.00
Purchase #4	$159.33	4.192%	$166.0091	$166.01	$166.00	$166.00
Purchase #5	$149.72	4.505%	$156.4649	$156.46	$156.45	$156.50
Purchase #6	$149.62	5.788%	$158.28	$158.28	$158.30	$158.30
Purchase #7	$59.69	8.354%	$64.6765	$64.68	$64.70	$64.70
7 purchase totals =	$1,010.02		$1,096.8605	$1,096.86	$1,096.85	$1,096.90