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	$181.62	8.436%	$196.9415	$196.94	$196.95	$196.90
Purchase #2	$159.47	4.671%	$166.9188	$166.92	$166.90	$166.90
Purchase #3	$152.68	9.427%	$167.0731	$167.07	$167.05	$167.10
Purchase #4	$231.78	5.302%	$244.069	$244.07	$244.05	$244.10
Purchase #5	$166.86	3.494%	$172.6901	$172.69	$172.70	$172.70
Purchase #6	$63.67	3.697%	$66.0239	$66.02	$66.00	$66.00
Purchase #7	$67.32	6.154%	$71.4629	$71.46	$71.45	$71.50
7 purchase totals =	$1,023.40		$1,085.1793	$1,085.17	$1,085.10	$1,085.20