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	$161.33	5.265%	$169.824	$169.82	$169.80	$169.80
Purchase #2	$27.54	7.531%	$29.614	$29.61	$29.60	$29.60
Purchase #3	$33.51	7.767%	$36.1127	$36.11	$36.10	$36.10
Purchase #4	$118.82	10.608%	$131.4244	$131.42	$131.40	$131.40
Purchase #5	$94.32	9.610%	$103.3842	$103.38	$103.40	$103.40
Purchase #6	$38.72	5.449%	$40.8299	$40.83	$40.85	$40.80
Purchase #7	$194.80	8.334%	$211.0346	$211.03	$211.05	$211.00
7 purchase totals =	$669.04		$722.2238	$722.20	$722.20	$722.10