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	$196.35	7.788%	$211.6417	$211.64	$211.65	$211.60
Purchase #2	$194.73	10.716%	$215.5973	$215.60	$215.60	$215.60
Purchase #3	$140.70	9.749%	$154.4168	$154.42	$154.40	$154.40
Purchase #4	$38.85	3.399%	$40.1705	$40.17	$40.15	$40.20
Purchase #5	$165.60	11.498%	$184.6407	$184.64	$184.65	$184.60
Purchase #6	$131.35	12.799%	$148.1615	$148.16	$148.15	$148.20
Purchase #7	$17.28	12.153%	$19.38	$19.38	$19.40	$19.40
7 purchase totals =	$884.86		$974.0085	$974.01	$974.00	$974.00