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	$80.62	5.722%	$85.2331	$85.23	$85.25	$85.20
Purchase #2	$85.98	11.650%	$95.9967	$96.00	$96.00	$96.00
Purchase #3	$209.69	6.266%	$222.8292	$222.83	$222.85	$222.80
Purchase #4	$194.92	11.193%	$216.7374	$216.74	$216.75	$216.70
Purchase #5	$96.60	7.761%	$104.0971	$104.10	$104.10	$104.10
Purchase #6	$89.88	11.690%	$100.387	$100.39	$100.40	$100.40
Purchase #7	$65.32	11.350%	$72.7338	$72.73	$72.75	$72.70
7 purchase totals =	$823.01		$898.0143	$898.02	$898.10	$897.90