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	$197.70	9.390%	$216.264	$216.26	$216.25	$216.30
Purchase #2	$225.69	8.630%	$245.167	$245.17	$245.15	$245.20
Purchase #3	$89.94	6.698%	$95.9642	$95.96	$95.95	$96.00
Purchase #4	$143.91	6.656%	$153.4886	$153.49	$153.50	$153.50
Purchase #5	$100.71	9.556%	$110.3338	$110.33	$110.35	$110.30
Purchase #6	$56.40	5.575%	$59.5443	$59.54	$59.55	$59.50
Purchase #7	$77.33	10.589%	$85.5185	$85.52	$85.50	$85.50
7 purchase totals =	$891.68		$966.2804	$966.27	$966.25	$966.30