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	$175.37	10.504%	$193.7909	$193.79	$193.80	$193.80
Purchase #2	$6.77	10.369%	$7.472	$7.47	$7.45	$7.50
Purchase #3	$156.27	6.525%	$166.4666	$166.47	$166.45	$166.50
Purchase #4	$211.81	11.410%	$235.9775	$235.98	$236.00	$236.00
Purchase #5	$248.83	8.700%	$270.4782	$270.48	$270.50	$270.50
Purchase #6	$151.43	11.149%	$168.3129	$168.31	$168.30	$168.30
Purchase #7	$18.82	11.726%	$21.0268	$21.03	$21.05	$21.00
7 purchase totals =	$969.30		$1,063.5249	$1,063.53	$1,063.55	$1,063.60