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	$182.65	9.203%	$199.4593	$199.46	$199.45	$199.50
Purchase #2	$160.91	7.205%	$172.5036	$172.50	$172.50	$172.50
Purchase #3	$214.36	3.846%	$222.6043	$222.60	$222.60	$222.60
Purchase #4	$19.39	8.124%	$20.9652	$20.97	$20.95	$21.00
Purchase #5	$61.69	9.640%	$67.6369	$67.64	$67.65	$67.60
Purchase #6	$206.51	3.326%	$213.3785	$213.38	$213.40	$213.40
Purchase #7	$166.44	7.665%	$179.1976	$179.20	$179.20	$179.20
7 purchase totals =	$1,011.95		$1,075.7454	$1,075.75	$1,075.75	$1,075.80