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	$153.62	5.536%	$162.1244	$162.12	$162.10	$162.10
Purchase #2	$215.79	5.444%	$227.5376	$227.54	$227.55	$227.50
Purchase #3	$30.46	11.143%	$33.8542	$33.85	$33.85	$33.90
Purchase #4	$19.56	13.108%	$22.1239	$22.12	$22.10	$22.10
Purchase #5	$142.94	6.554%	$152.3083	$152.31	$152.30	$152.30
Purchase #6	$75.39	8.380%	$81.7077	$81.71	$81.70	$81.70
Purchase #7	$101.62	3.677%	$105.3566	$105.36	$105.35	$105.40
7 purchase totals =	$739.38		$785.0127	$785.01	$784.95	$785.00