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	$191.75	3.159%	$197.8074	$197.81	$197.80	$197.80
Purchase #2	$72.62	8.296%	$78.6446	$78.64	$78.65	$78.60
Purchase #3	$80.85	7.133%	$86.617	$86.62	$86.60	$86.60
Purchase #4	$77.49	5.852%	$82.0247	$82.02	$82.00	$82.00
Purchase #5	$28.81	10.811%	$31.9246	$31.92	$31.90	$31.90
Purchase #6	$121.92	4.247%	$127.0979	$127.10	$127.10	$127.10
Purchase #7	$95.67	5.438%	$100.8725	$100.87	$100.85	$100.90
7 purchase totals =	$669.11		$704.9887	$704.98	$704.90	$704.90