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	$213.59	4.143%	$222.439	$222.44	$222.45	$222.40
Purchase #2	$221.49	5.461%	$233.5856	$233.59	$233.60	$233.60
Purchase #3	$42.69	11.119%	$47.4367	$47.44	$47.45	$47.40
Purchase #4	$203.73	11.659%	$227.4829	$227.48	$227.50	$227.50
Purchase #5	$103.30	12.331%	$116.0379	$116.04	$116.05	$116.00
Purchase #6	$188.31	4.257%	$196.3264	$196.33	$196.35	$196.30
Purchase #7	$23.41	12.501%	$26.3365	$26.34	$26.35	$26.30
7 purchase totals =	$996.52		$1,069.6450	$1,069.66	$1,069.75	$1,069.50