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	$185.30	9.474%	$202.8553	$202.86	$202.85	$202.90
Purchase #2	$93.59	4.147%	$97.4712	$97.47	$97.45	$97.50
Purchase #3	$42.82	8.815%	$46.5946	$46.59	$46.60	$46.60
Purchase #4	$57.29	7.241%	$61.4384	$61.44	$61.45	$61.40
Purchase #5	$199.96	6.652%	$213.2613	$213.26	$213.25	$213.30
Purchase #6	$246.37	13.410%	$279.4082	$279.41	$279.40	$279.40
Purchase #7	$170.58	8.801%	$185.5927	$185.59	$185.60	$185.60
7 purchase totals =	$995.91		$1,086.6217	$1,086.62	$1,086.60	$1,086.70