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	$194.54	5.153%	$204.5646	$204.56	$204.55	$204.60
Purchase #2	$200.85	12.253%	$225.4602	$225.46	$225.45	$225.50
Purchase #3	$201.50	3.692%	$208.9394	$208.94	$208.95	$208.90
Purchase #4	$94.43	9.483%	$103.3848	$103.38	$103.40	$103.40
Purchase #5	$73.72	5.372%	$77.6802	$77.68	$77.70	$77.70
Purchase #6	$170.25	10.186%	$187.5917	$187.59	$187.60	$187.60
Purchase #7	$37.71	3.104%	$38.8805	$38.88	$38.90	$38.90
7 purchase totals =	$973.00		$1,046.5014	$1,046.49	$1,046.55	$1,046.60