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	$187.66	3.398%	$194.0367	$194.04	$194.05	$194.00
Purchase #2	$53.99	4.649%	$56.5	$56.50	$56.50	$56.50
Purchase #3	$226.58	12.790%	$255.5596	$255.56	$255.55	$255.60
Purchase #4	$12.68	13.757%	$14.4244	$14.42	$14.40	$14.40
Purchase #5	$34.41	8.711%	$37.4075	$37.41	$37.40	$37.40
Purchase #6	$205.66	8.224%	$222.5735	$222.57	$222.55	$222.60
Purchase #7	$218.26	9.718%	$239.4705	$239.47	$239.45	$239.50
7 purchase totals =	$939.24		$1,019.9722	$1,019.97	$1,019.90	$1,020.00