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	$196.75	8.739%	$213.944	$213.94	$213.95	$213.90
Purchase #2	$142.93	5.170%	$150.3195	$150.32	$150.30	$150.30
Purchase #3	$169.50	6.761%	$180.9599	$180.96	$180.95	$181.00
Purchase #4	$40.56	12.188%	$45.5035	$45.50	$45.50	$45.50
Purchase #5	$167.26	10.307%	$184.4995	$184.50	$184.50	$184.50
Purchase #6	$87.32	9.284%	$95.4268	$95.43	$95.45	$95.40
Purchase #7	$156.48	3.590%	$162.0976	$162.10	$162.10	$162.10
7 purchase totals =	$960.80		$1,032.7508	$1,032.75	$1,032.75	$1,032.70