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	$213.37	4.374%	$222.7028	$222.70	$222.70	$222.70
Purchase #2	$196.98	7.404%	$211.5644	$211.56	$211.55	$211.60
Purchase #3	$195.41	10.235%	$215.4102	$215.41	$215.40	$215.40
Purchase #4	$234.74	4.469%	$245.2305	$245.23	$245.25	$245.20
Purchase #5	$41.32	10.558%	$45.6826	$45.68	$45.70	$45.70
Purchase #6	$81.46	5.477%	$85.9216	$85.92	$85.90	$85.90
Purchase #7	$155.25	8.874%	$169.0269	$169.03	$169.05	$169.00
7 purchase totals =	$1,118.53		$1,195.5390	$1,195.53	$1,195.55	$1,195.50