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	$184.95	7.727%	$199.2411	$199.24	$199.25	$199.20
Purchase #2	$198.89	5.458%	$209.7454	$209.75	$209.75	$209.70
Purchase #3	$89.45	12.114%	$100.286	$100.29	$100.30	$100.30
Purchase #4	$121.97	7.747%	$131.419	$131.42	$131.40	$131.40
Purchase #5	$248.69	7.238%	$266.6902	$266.69	$266.70	$266.70
Purchase #6	$190.54	12.237%	$213.8564	$213.86	$213.85	$213.90
Purchase #7	$32.65	6.502%	$34.7729	$34.77	$34.75	$34.80
7 purchase totals =	$1,067.14		$1,156.0110	$1,156.02	$1,156.00	$1,156.00