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	$94.34	12.791%	$106.407	$106.41	$106.40	$106.40
Purchase #2	$241.65	5.869%	$255.8324	$255.83	$255.85	$255.80
Purchase #3	$176.54	8.303%	$191.1981	$191.20	$191.20	$191.20
Purchase #4	$228.58	3.382%	$236.3106	$236.31	$236.30	$236.30
Purchase #5	$45.32	3.216%	$46.7775	$46.78	$46.80	$46.80
Purchase #6	$189.85	12.654%	$213.8736	$213.87	$213.85	$213.90
Purchase #7	$57.37	3.483%	$59.3682	$59.37	$59.35	$59.40
7 purchase totals =	$1,033.65		$1,109.7674	$1,109.77	$1,109.75	$1,109.80