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	$119.86	6.625%	$127.8007	$127.80	$127.80	$127.80
Purchase #2	$111.86	11.181%	$124.3671	$124.37	$124.35	$124.40
Purchase #3	$20.49	7.619%	$22.0511	$22.05	$22.05	$22.10
Purchase #4	$25.70	6.523%	$27.3764	$27.38	$27.40	$27.40
Purchase #5	$197.50	6.244%	$209.8319	$209.83	$209.85	$209.80
Purchase #6	$223.72	6.856%	$239.0582	$239.06	$239.05	$239.10
Purchase #7	$238.48	11.465%	$265.8217	$265.82	$265.80	$265.80
7 purchase totals =	$937.61		$1,016.3071	$1,016.31	$1,016.30	$1,016.40