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	$82.52	4.141%	$85.9372	$85.94	$85.95	$85.90
Purchase #2	$41.48	10.343%	$45.7703	$45.77	$45.75	$45.80
Purchase #3	$55.59	9.762%	$61.0167	$61.02	$61.00	$61.00
Purchase #4	$181.32	8.232%	$196.2463	$196.25	$196.25	$196.20
Purchase #5	$184.89	3.233%	$190.8675	$190.87	$190.85	$190.90
Purchase #6	$171.97	7.598%	$185.0363	$185.04	$185.05	$185.00
Purchase #7	$207.66	6.351%	$220.8485	$220.85	$220.85	$220.80
7 purchase totals =	$925.43		$985.7228	$985.74	$985.70	$985.60