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	$202.47	4.492%	$211.565	$211.57	$211.55	$211.60
Purchase #2	$145.98	3.450%	$151.0163	$151.02	$151.00	$151.00
Purchase #3	$175.37	6.365%	$186.5323	$186.53	$186.55	$186.50
Purchase #4	$164.84	10.608%	$182.3262	$182.33	$182.35	$182.30
Purchase #5	$118.72	6.437%	$126.362	$126.36	$126.35	$126.40
Purchase #6	$248.88	11.162%	$276.66	$276.66	$276.65	$276.70
Purchase #7	$59.32	3.860%	$61.6098	$61.61	$61.60	$61.60
7 purchase totals =	$1,115.58		$1,196.0716	$1,196.08	$1,196.05	$1,196.10