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	$188.43	7.346%	$202.2721	$202.27	$202.25	$202.30
Purchase #2	$52.50	6.238%	$55.775	$55.78	$55.80	$55.80
Purchase #3	$230.47	4.469%	$240.7697	$240.77	$240.75	$240.80
Purchase #4	$77.59	3.448%	$80.2653	$80.27	$80.25	$80.30
Purchase #5	$34.83	13.171%	$39.4175	$39.42	$39.40	$39.40
Purchase #6	$151.49	13.401%	$171.7912	$171.79	$171.80	$171.80
Purchase #7	$199.26	13.685%	$226.5287	$226.53	$226.55	$226.50
7 purchase totals =	$934.57		$1,016.8195	$1,016.83	$1,016.80	$1,016.90