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	$200.45	7.495%	$215.4737	$215.47	$215.45	$215.50
Purchase #2	$75.58	8.854%	$82.2719	$82.27	$82.25	$82.30
Purchase #3	$152.46	9.515%	$166.9666	$166.97	$166.95	$167.00
Purchase #4	$140.51	5.609%	$148.3912	$148.39	$148.40	$148.40
Purchase #5	$184.88	6.218%	$196.3758	$196.38	$196.40	$196.40
Purchase #6	$148.27	8.330%	$160.6209	$160.62	$160.60	$160.60
Purchase #7	$118.25	5.521%	$124.7786	$124.78	$124.80	$124.80
7 purchase totals =	$1,020.40		$1,094.8787	$1,094.88	$1,094.85	$1,095.00