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	$188.56	13.481%	$213.9798	$213.98	$214.00	$214.00
Purchase #2	$94.89	4.260%	$98.9323	$98.93	$98.95	$98.90
Purchase #3	$170.77	13.497%	$193.8188	$193.82	$193.80	$193.80
Purchase #4	$134.65	10.268%	$148.4759	$148.48	$148.50	$148.50
Purchase #5	$106.52	5.757%	$112.6524	$112.65	$112.65	$112.70
Purchase #6	$59.46	13.263%	$67.3462	$67.35	$67.35	$67.30
Purchase #7	$97.78	11.483%	$109.0081	$109.01	$109.00	$109.00
7 purchase totals =	$852.63		$944.2135	$944.22	$944.25	$944.20