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	$171.71	11.372%	$191.2369	$191.24	$191.25	$191.20
Purchase #2	$96.49	11.153%	$107.2515	$107.25	$107.25	$107.30
Purchase #3	$7.37	4.544%	$7.7049	$7.70	$7.70	$7.70
Purchase #4	$191.92	8.844%	$208.8934	$208.89	$208.90	$208.90
Purchase #5	$206.43	12.306%	$231.8333	$231.83	$231.85	$231.80
Purchase #6	$89.80	6.798%	$95.9046	$95.90	$95.90	$95.90
Purchase #7	$237.40	6.643%	$253.1705	$253.17	$253.15	$253.20
7 purchase totals =	$1,001.12		$1,095.9951	$1,095.98	$1,096.00	$1,096.00