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	$146.25	4.231%	$152.4378	$152.44	$152.45	$152.40
Purchase #2	$45.36	9.311%	$49.5835	$49.58	$49.60	$49.60
Purchase #3	$45.97	9.724%	$50.4401	$50.44	$50.45	$50.40
Purchase #4	$144.72	6.345%	$153.9025	$153.90	$153.90	$153.90
Purchase #5	$228.88	5.190%	$240.7589	$240.76	$240.75	$240.80
Purchase #6	$236.99	8.115%	$256.2217	$256.22	$256.20	$256.20
Purchase #7	$99.29	12.299%	$111.5017	$111.50	$111.50	$111.50
7 purchase totals =	$947.46		$1,014.8462	$1,014.84	$1,014.85	$1,014.80