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	$94.59	7.671%	$101.846	$101.85	$101.85	$101.80
Purchase #2	$43.69	8.449%	$47.3814	$47.38	$47.40	$47.40
Purchase #3	$25.57	7.799%	$27.5642	$27.56	$27.55	$27.60
Purchase #4	$19.25	9.722%	$21.1215	$21.12	$21.10	$21.10
Purchase #5	$184.30	8.531%	$200.0226	$200.02	$200.00	$200.00
Purchase #6	$102.90	3.596%	$106.6003	$106.60	$106.60	$106.60
Purchase #7	$31.29	7.157%	$33.5294	$33.53	$33.55	$33.50
7 purchase totals =	$501.59		$538.0654	$538.06	$538.05	$538.00