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	$184.31	13.650%	$209.4683	$209.47	$209.45	$209.50
Purchase #2	$213.89	10.591%	$236.5431	$236.54	$236.55	$236.50
Purchase #3	$215.81	5.858%	$228.4521	$228.45	$228.45	$228.50
Purchase #4	$42.67	3.809%	$44.2953	$44.30	$44.30	$44.30
Purchase #5	$63.76	5.238%	$67.0997	$67.10	$67.10	$67.10
Purchase #6	$113.45	11.136%	$126.0838	$126.08	$126.10	$126.10
Purchase #7	$147.38	5.466%	$155.4358	$155.44	$155.45	$155.40
7 purchase totals =	$981.27		$1,067.3781	$1,067.38	$1,067.40	$1,067.40