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	$116.26	13.664%	$132.1458	$132.15	$132.15	$132.10
Purchase #2	$67.67	5.170%	$71.1685	$71.17	$71.15	$71.20
Purchase #3	$22.26	12.466%	$25.0349	$25.03	$25.05	$25.00
Purchase #4	$62.98	6.618%	$67.148	$67.15	$67.15	$67.10
Purchase #5	$222.70	5.339%	$234.59	$234.59	$234.60	$234.60
Purchase #6	$86.44	10.516%	$95.53	$95.53	$95.55	$95.50
Purchase #7	$247.86	6.598%	$264.2138	$264.21	$264.20	$264.20
7 purchase totals =	$826.17		$889.8310	$889.83	$889.85	$889.70