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	$119.57	5.494%	$126.1392	$126.14	$126.15	$126.10
Purchase #2	$89.28	12.501%	$100.4409	$100.44	$100.45	$100.40
Purchase #3	$160.60	5.643%	$169.6627	$169.66	$169.65	$169.70
Purchase #4	$138.41	3.283%	$142.954	$142.95	$142.95	$143.00
Purchase #5	$72.89	11.580%	$81.3307	$81.33	$81.35	$81.30
Purchase #6	$187.64	4.735%	$196.5248	$196.52	$196.50	$196.50
Purchase #7	$242.42	6.379%	$257.884	$257.88	$257.90	$257.90
7 purchase totals =	$1,010.81		$1,074.9363	$1,074.92	$1,074.95	$1,074.90