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	$63.66	13.499%	$72.2535	$72.25	$72.25	$72.30
Purchase #2	$229.45	11.715%	$256.3301	$256.33	$256.35	$256.30
Purchase #3	$201.59	7.865%	$217.4451	$217.45	$217.45	$217.40
Purchase #4	$197.28	12.646%	$222.228	$222.23	$222.25	$222.20
Purchase #5	$23.66	3.776%	$24.5534	$24.55	$24.55	$24.60
Purchase #6	$167.48	4.479%	$174.9814	$174.98	$175.00	$175.00
Purchase #7	$117.91	7.564%	$126.8287	$126.83	$126.85	$126.80
7 purchase totals =	$1,001.03		$1,094.6202	$1,094.62	$1,094.70	$1,094.60