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	$115.93	9.194%	$126.5886	$126.59	$126.60	$126.60
Purchase #2	$188.59	4.165%	$196.4448	$196.44	$196.45	$196.40
Purchase #3	$236.93	13.244%	$268.309	$268.31	$268.30	$268.30
Purchase #4	$248.26	5.316%	$261.4575	$261.46	$261.45	$261.50
Purchase #5	$129.33	9.864%	$142.0871	$142.09	$142.10	$142.10
Purchase #6	$114.58	3.218%	$118.2672	$118.27	$118.25	$118.30
Purchase #7	$62.97	7.324%	$67.5819	$67.58	$67.60	$67.60
7 purchase totals =	$1,096.59		$1,180.7361	$1,180.74	$1,180.75	$1,180.80