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	$199.46	3.319%	$206.0801	$206.08	$206.10	$206.10
Purchase #2	$186.35	7.479%	$200.2871	$200.29	$200.30	$200.30
Purchase #3	$14.89	6.725%	$15.8914	$15.89	$15.90	$15.90
Purchase #4	$86.43	11.253%	$96.156	$96.16	$96.15	$96.20
Purchase #5	$113.76	4.482%	$118.8587	$118.86	$118.85	$118.90
Purchase #6	$198.90	4.671%	$208.1906	$208.19	$208.20	$208.20
Purchase #7	$192.78	8.327%	$208.8328	$208.83	$208.85	$208.80
7 purchase totals =	$992.57		$1,054.2967	$1,054.30	$1,054.35	$1,054.40