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	$191.60	4.480%	$200.1837	$200.18	$200.20	$200.20
Purchase #2	$174.96	13.347%	$198.3119	$198.31	$198.30	$198.30
Purchase #3	$112.86	10.624%	$124.8502	$124.85	$124.85	$124.90
Purchase #4	$184.44	3.600%	$191.0798	$191.08	$191.10	$191.10
Purchase #5	$118.31	4.801%	$123.9901	$123.99	$124.00	$124.00
Purchase #6	$40.43	12.294%	$45.4005	$45.40	$45.40	$45.40
Purchase #7	$205.53	9.805%	$225.6822	$225.68	$225.70	$225.70
7 purchase totals =	$1,028.13		$1,109.4984	$1,109.49	$1,109.55	$1,109.60