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	$183.92	6.513%	$195.8987	$195.90	$195.90	$195.90
Purchase #2	$43.35	4.736%	$45.4031	$45.40	$45.40	$45.40
Purchase #3	$177.64	5.382%	$187.2006	$187.20	$187.20	$187.20
Purchase #4	$60.29	11.525%	$67.2384	$67.24	$67.25	$67.20
Purchase #5	$179.34	8.440%	$194.4763	$194.48	$194.50	$194.50
Purchase #6	$191.26	7.663%	$205.9163	$205.92	$205.90	$205.90
Purchase #7	$230.52	10.735%	$255.2663	$255.27	$255.25	$255.30
7 purchase totals =	$1,066.32		$1,151.3997	$1,151.41	$1,151.40	$1,151.40