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	$206.59	4.532%	$215.9527	$215.95	$215.95	$216.00
Purchase #2	$134.73	12.775%	$151.9418	$151.94	$151.95	$151.90
Purchase #3	$131.54	7.578%	$141.5081	$141.51	$141.50	$141.50
Purchase #4	$154.75	12.753%	$174.4853	$174.49	$174.50	$174.50
Purchase #5	$204.58	8.572%	$222.1166	$222.12	$222.10	$222.10
Purchase #6	$94.67	11.433%	$105.4936	$105.49	$105.50	$105.50
Purchase #7	$157.82	8.280%	$170.8875	$170.89	$170.90	$170.90
7 purchase totals =	$1,084.68		$1,182.3856	$1,182.39	$1,182.40	$1,182.40