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	$69.36	3.863%	$72.0394	$72.04	$72.05	$72.00
Purchase #2	$67.68	4.727%	$70.8792	$70.88	$70.90	$70.90
Purchase #3	$152.51	10.616%	$168.7005	$168.70	$168.70	$168.70
Purchase #4	$215.69	5.392%	$227.32	$227.32	$227.30	$227.30
Purchase #5	$202.80	4.587%	$212.1024	$212.10	$212.10	$212.10
Purchase #6	$107.70	6.158%	$114.3322	$114.33	$114.35	$114.30
Purchase #7	$139.46	8.704%	$151.5986	$151.60	$151.60	$151.60
7 purchase totals =	$955.20		$1,016.9723	$1,016.97	$1,017.00	$1,016.90