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	$235.37	4.706%	$246.4465	$246.45	$246.45	$246.40
Purchase #2	$9.51	9.651%	$10.4278	$10.43	$10.45	$10.40
Purchase #3	$224.97	6.209%	$238.9384	$238.94	$238.95	$238.90
Purchase #4	$213.50	4.497%	$223.1011	$223.10	$223.10	$223.10
Purchase #5	$86.60	12.435%	$97.3687	$97.37	$97.35	$97.40
Purchase #6	$182.76	4.162%	$190.3665	$190.37	$190.35	$190.40
Purchase #7	$78.45	9.406%	$85.829	$85.83	$85.85	$85.80
7 purchase totals =	$1,031.16		$1,092.4780	$1,092.49	$1,092.50	$1,092.40