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	$200.64	7.437%	$215.5616	$215.56	$215.55	$215.60
Purchase #2	$169.31	7.809%	$182.5314	$182.53	$182.55	$182.50
Purchase #3	$69.27	5.262%	$72.915	$72.92	$72.90	$72.90
Purchase #4	$203.80	13.788%	$231.8999	$231.90	$231.90	$231.90
Purchase #5	$109.30	3.639%	$113.2774	$113.28	$113.30	$113.30
Purchase #6	$224.87	8.625%	$244.265	$244.27	$244.25	$244.30
Purchase #7	$186.83	12.204%	$209.6307	$209.63	$209.65	$209.60
7 purchase totals =	$1,164.02		$1,270.0810	$1,270.09	$1,270.10	$1,270.10