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	$198.29	7.260%	$212.6859	$212.69	$212.70	$212.70
Purchase #2	$42.60	7.535%	$45.8099	$45.81	$45.80	$45.80
Purchase #3	$9.38	7.457%	$10.0795	$10.08	$10.10	$10.10
Purchase #4	$195.90	11.469%	$218.3678	$218.37	$218.35	$218.40
Purchase #5	$136.49	13.767%	$155.2806	$155.28	$155.30	$155.30
Purchase #6	$182.81	9.541%	$200.2519	$200.25	$200.25	$200.30
Purchase #7	$118.50	7.256%	$127.0984	$127.10	$127.10	$127.10
7 purchase totals =	$883.97		$969.5740	$969.58	$969.60	$969.70