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	$181.98	7.769%	$196.118	$196.12	$196.10	$196.10
Purchase #2	$169.91	7.685%	$182.9676	$182.97	$182.95	$183.00
Purchase #3	$27.89	8.439%	$30.2436	$30.24	$30.25	$30.20
Purchase #4	$8.56	3.165%	$8.8309	$8.83	$8.85	$8.80
Purchase #5	$242.85	6.452%	$258.5187	$258.52	$258.50	$258.50
Purchase #6	$226.69	4.690%	$237.3218	$237.32	$237.30	$237.30
Purchase #7	$163.82	5.265%	$172.4451	$172.45	$172.45	$172.40
7 purchase totals =	$1,021.70		$1,086.4457	$1,086.45	$1,086.40	$1,086.30