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	$174.94	11.245%	$194.612	$194.61	$194.60	$194.60
Purchase #2	$105.59	10.179%	$116.338	$116.34	$116.35	$116.30
Purchase #3	$167.39	3.865%	$173.8596	$173.86	$173.85	$173.90
Purchase #4	$232.87	9.653%	$255.3489	$255.35	$255.35	$255.30
Purchase #5	$115.35	7.171%	$123.6217	$123.62	$123.60	$123.60
Purchase #6	$14.29	4.500%	$14.9331	$14.93	$14.95	$14.90
Purchase #7	$201.26	13.222%	$227.8706	$227.87	$227.85	$227.90
7 purchase totals =	$1,011.69		$1,106.5839	$1,106.58	$1,106.55	$1,106.50