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	$193.43	6.660%	$206.3124	$206.31	$206.30	$206.30
Purchase #2	$76.72	12.171%	$86.0576	$86.06	$86.05	$86.10
Purchase #3	$199.65	4.411%	$208.4566	$208.46	$208.45	$208.50
Purchase #4	$219.36	5.714%	$231.8942	$231.89	$231.90	$231.90
Purchase #5	$38.44	6.659%	$40.9997	$41.00	$41.00	$41.00
Purchase #6	$69.74	12.848%	$78.7002	$78.70	$78.70	$78.70
Purchase #7	$199.52	6.571%	$212.6305	$212.63	$212.65	$212.60
7 purchase totals =	$996.86		$1,065.0512	$1,065.05	$1,065.05	$1,065.10