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	$195.85	7.307%	$210.1608	$210.16	$210.15	$210.20
Purchase #2	$111.59	10.206%	$122.9789	$122.98	$123.00	$123.00
Purchase #3	$225.38	13.169%	$255.0603	$255.06	$255.05	$255.10
Purchase #4	$40.95	10.245%	$45.1453	$45.15	$45.15	$45.10
Purchase #5	$121.30	6.832%	$129.5872	$129.59	$129.60	$129.60
Purchase #6	$82.37	8.179%	$89.107	$89.11	$89.10	$89.10
Purchase #7	$226.69	6.689%	$241.8533	$241.85	$241.85	$241.90
7 purchase totals =	$1,004.13		$1,093.8928	$1,093.90	$1,093.90	$1,094.00