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	$138.35	10.566%	$152.9681	$152.97	$152.95	$153.00
Purchase #2	$197.37	8.400%	$213.9491	$213.95	$213.95	$213.90
Purchase #3	$168.54	10.328%	$185.9468	$185.95	$185.95	$185.90
Purchase #4	$116.69	3.684%	$120.9889	$120.99	$121.00	$121.00
Purchase #5	$70.44	11.395%	$78.4666	$78.47	$78.45	$78.50
Purchase #6	$229.93	4.616%	$240.5436	$240.54	$240.55	$240.50
Purchase #7	$49.25	9.761%	$54.0573	$54.06	$54.05	$54.10
7 purchase totals =	$970.57		$1,046.9204	$1,046.93	$1,046.90	$1,046.90