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	$69.68	5.372%	$73.4232	$73.42	$73.40	$73.40
Purchase #2	$241.86	5.270%	$254.606	$254.61	$254.60	$254.60
Purchase #3	$148.25	12.500%	$166.7813	$166.78	$166.80	$166.80
Purchase #4	$174.27	12.819%	$196.6097	$196.61	$196.60	$196.60
Purchase #5	$21.85	7.802%	$23.5547	$23.55	$23.55	$23.60
Purchase #6	$116.82	5.565%	$123.321	$123.32	$123.30	$123.30
Purchase #7	$159.34	12.438%	$179.1587	$179.16	$179.15	$179.20
7 purchase totals =	$932.07		$1,017.4546	$1,017.45	$1,017.40	$1,017.50