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	$59.95	12.500%	$67.4438	$67.44	$67.45	$67.40
Purchase #2	$161.71	8.134%	$174.8635	$174.86	$174.85	$174.90
Purchase #3	$231.58	5.337%	$243.9394	$243.94	$243.95	$243.90
Purchase #4	$131.99	7.270%	$141.5857	$141.59	$141.60	$141.60
Purchase #5	$211.89	3.637%	$219.5964	$219.60	$219.60	$219.60
Purchase #6	$236.69	4.136%	$246.4795	$246.48	$246.50	$246.50
Purchase #7	$107.45	3.739%	$111.4676	$111.47	$111.45	$111.50
7 purchase totals =	$1,141.26		$1,205.3759	$1,205.38	$1,205.40	$1,205.40