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	$209.82	7.560%	$225.6824	$225.68	$225.70	$225.70
Purchase #2	$5.80	10.827%	$6.428	$6.43	$6.45	$6.40
Purchase #3	$74.39	10.740%	$82.3795	$82.38	$82.40	$82.40
Purchase #4	$169.87	6.778%	$181.3838	$181.38	$181.40	$181.40
Purchase #5	$237.75	6.840%	$254.0121	$254.01	$254.00	$254.00
Purchase #6	$44.72	4.702%	$46.8227	$46.82	$46.80	$46.80
Purchase #7	$33.85	11.436%	$37.7211	$37.72	$37.70	$37.70
7 purchase totals =	$776.20		$834.4296	$834.42	$834.45	$834.40