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	$213.62	13.635%	$242.7471	$242.75	$242.75	$242.70
Purchase #2	$30.97	8.470%	$33.5932	$33.59	$33.60	$33.60
Purchase #3	$221.82	4.222%	$231.1852	$231.19	$231.20	$231.20
Purchase #4	$174.38	12.806%	$196.7111	$196.71	$196.70	$196.70
Purchase #5	$246.30	10.410%	$271.9398	$271.94	$271.95	$271.90
Purchase #6	$139.77	6.326%	$148.6119	$148.61	$148.60	$148.60
Purchase #7	$222.69	4.744%	$233.2544	$233.25	$233.25	$233.30
7 purchase totals =	$1,249.55		$1,358.0427	$1,358.04	$1,358.05	$1,358.00