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	$76.33	8.561%	$82.8646	$82.86	$82.85	$82.90
Purchase #2	$25.71	11.587%	$28.689	$28.69	$28.70	$28.70
Purchase #3	$57.27	12.851%	$64.6298	$64.63	$64.65	$64.60
Purchase #4	$31.27	5.343%	$32.9408	$32.94	$32.95	$32.90
Purchase #5	$43.91	11.410%	$48.9201	$48.92	$48.90	$48.90
Purchase #6	$210.88	5.590%	$222.6682	$222.67	$222.65	$222.70
Purchase #7	$65.81	3.788%	$68.3029	$68.30	$68.30	$68.30
7 purchase totals =	$511.18		$549.0154	$549.01	$549.00	$549.00