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	$97.29	9.237%	$106.2767	$106.28	$106.30	$106.30
Purchase #2	$155.72	6.342%	$165.5958	$165.60	$165.60	$165.60
Purchase #3	$144.83	9.583%	$158.7091	$158.71	$158.70	$158.70
Purchase #4	$210.71	13.326%	$238.7892	$238.79	$238.80	$238.80
Purchase #5	$115.96	8.374%	$125.6705	$125.67	$125.65	$125.70
Purchase #6	$95.57	8.309%	$103.5109	$103.51	$103.50	$103.50
Purchase #7	$181.36	8.257%	$196.3349	$196.33	$196.35	$196.30
7 purchase totals =	$1,001.44		$1,094.8871	$1,094.89	$1,094.90	$1,094.90