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	$94.31	3.457%	$97.5703	$97.57	$97.55	$97.60
Purchase #2	$192.39	10.775%	$213.12	$213.12	$213.10	$213.10
Purchase #3	$14.96	3.257%	$15.4472	$15.45	$15.45	$15.40
Purchase #4	$127.47	9.858%	$140.036	$140.04	$140.05	$140.00
Purchase #5	$207.27	4.760%	$217.1361	$217.14	$217.15	$217.10
Purchase #6	$106.30	4.855%	$111.4609	$111.46	$111.45	$111.50
Purchase #7	$137.71	9.513%	$150.8104	$150.81	$150.80	$150.80
7 purchase totals =	$880.41		$945.5809	$945.59	$945.55	$945.50