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	$208.56	4.413%	$217.7638	$217.76	$217.75	$217.80
Purchase #2	$48.31	11.649%	$53.9376	$53.94	$53.95	$53.90
Purchase #3	$35.26	6.622%	$37.5949	$37.59	$37.60	$37.60
Purchase #4	$90.70	10.671%	$100.3786	$100.38	$100.40	$100.40
Purchase #5	$190.96	9.188%	$208.5054	$208.51	$208.50	$208.50
Purchase #6	$197.36	5.671%	$208.5523	$208.55	$208.55	$208.60
Purchase #7	$174.49	4.549%	$182.4276	$182.43	$182.45	$182.40
7 purchase totals =	$945.64		$1,009.1602	$1,009.16	$1,009.20	$1,009.20