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	$40.43	9.193%	$44.1467	$44.15	$44.15	$44.10
Purchase #2	$95.52	9.413%	$104.5113	$104.51	$104.50	$104.50
Purchase #3	$132.40	13.466%	$150.229	$150.23	$150.25	$150.20
Purchase #4	$231.40	5.210%	$243.4559	$243.46	$243.45	$243.50
Purchase #5	$153.57	5.587%	$162.15	$162.15	$162.15	$162.20
Purchase #6	$82.67	6.591%	$88.1188	$88.12	$88.10	$88.10
Purchase #7	$242.28	6.464%	$257.941	$257.94	$257.95	$257.90
7 purchase totals =	$978.27		$1,050.5527	$1,050.56	$1,050.55	$1,050.50