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	$65.56	9.154%	$71.5614	$71.56	$71.55	$71.60
Purchase #2	$183.31	5.650%	$193.667	$193.67	$193.65	$193.70
Purchase #3	$33.87	7.664%	$36.4658	$36.47	$36.45	$36.50
Purchase #4	$220.98	7.489%	$237.5292	$237.53	$237.55	$237.50
Purchase #5	$196.62	6.736%	$209.8643	$209.86	$209.85	$209.90
Purchase #6	$179.90	6.516%	$191.6223	$191.62	$191.60	$191.60
Purchase #7	$60.43	3.687%	$62.6581	$62.66	$62.65	$62.70
7 purchase totals =	$940.67		$1,003.3681	$1,003.37	$1,003.30	$1,003.50