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	$163.42	7.865%	$176.273	$176.27	$176.25	$176.30
Purchase #2	$54.32	9.643%	$59.5581	$59.56	$59.55	$59.60
Purchase #3	$27.77	5.706%	$29.3546	$29.35	$29.35	$29.40
Purchase #4	$92.98	8.138%	$100.5467	$100.55	$100.55	$100.50
Purchase #5	$185.41	6.803%	$198.0234	$198.02	$198.00	$198.00
Purchase #6	$169.53	6.657%	$180.8156	$180.82	$180.80	$180.80
Purchase #7	$5.82	12.776%	$6.5636	$6.56	$6.55	$6.60
7 purchase totals =	$699.25		$751.1350	$751.13	$751.05	$751.20