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	$92.61	5.685%	$97.8749	$97.87	$97.85	$97.90
Purchase #2	$82.48	3.451%	$85.3264	$85.33	$85.35	$85.30
Purchase #3	$193.63	7.456%	$208.0671	$208.07	$208.05	$208.10
Purchase #4	$136.73	4.261%	$142.5561	$142.56	$142.55	$142.60
Purchase #5	$223.54	6.584%	$238.2579	$238.26	$238.25	$238.30
Purchase #6	$127.83	5.346%	$134.6638	$134.66	$134.65	$134.70
Purchase #7	$95.86	10.389%	$105.8189	$105.82	$105.80	$105.80
7 purchase totals =	$952.68		$1,012.5651	$1,012.57	$1,012.50	$1,012.70