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	$155.89	11.601%	$173.9748	$173.97	$173.95	$174.00
Purchase #2	$131.83	7.650%	$141.915	$141.92	$141.90	$141.90
Purchase #3	$171.27	9.710%	$187.9003	$187.90	$187.90	$187.90
Purchase #4	$27.86	11.720%	$31.1252	$31.13	$31.15	$31.10
Purchase #5	$83.88	9.244%	$91.6339	$91.63	$91.65	$91.60
Purchase #6	$148.53	12.358%	$166.8853	$166.89	$166.90	$166.90
Purchase #7	$213.33	4.347%	$222.6035	$222.60	$222.60	$222.60
7 purchase totals =	$932.59		$1,016.0380	$1,016.04	$1,016.05	$1,016.00