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	$53.38	11.235%	$59.3772	$59.38	$59.40	$59.40
Purchase #2	$172.99	12.380%	$194.4062	$194.41	$194.40	$194.40
Purchase #3	$242.32	11.338%	$269.7942	$269.79	$269.80	$269.80
Purchase #4	$148.61	7.129%	$159.2044	$159.20	$159.20	$159.20
Purchase #5	$151.75	9.826%	$166.661	$166.66	$166.65	$166.70
Purchase #6	$161.46	11.173%	$179.4999	$179.50	$179.50	$179.50
Purchase #7	$181.32	3.496%	$187.6589	$187.66	$187.65	$187.70
7 purchase totals =	$1,111.83		$1,216.6018	$1,216.60	$1,216.60	$1,216.70