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	$182.95	12.786%	$206.342	$206.34	$206.35	$206.30
Purchase #2	$81.98	10.450%	$90.5469	$90.55	$90.55	$90.50
Purchase #3	$87.27	10.442%	$96.3827	$96.38	$96.40	$96.40
Purchase #4	$176.45	8.386%	$191.2471	$191.25	$191.25	$191.20
Purchase #5	$176.56	12.333%	$198.3351	$198.34	$198.35	$198.30
Purchase #6	$68.83	13.182%	$77.9032	$77.90	$77.90	$77.90
Purchase #7	$91.74	11.159%	$101.9773	$101.98	$102.00	$102.00
7 purchase totals =	$865.78		$962.7343	$962.74	$962.80	$962.60