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	$205.57	9.870%	$225.8598	$225.86	$225.85	$225.90
Purchase #2	$146.75	4.108%	$152.7785	$152.78	$152.80	$152.80
Purchase #3	$62.30	6.541%	$66.375	$66.38	$66.40	$66.40
Purchase #4	$163.31	12.222%	$183.2697	$183.27	$183.25	$183.30
Purchase #5	$187.59	6.548%	$199.8734	$199.87	$199.85	$199.90
Purchase #6	$126.45	5.267%	$133.1101	$133.11	$133.10	$133.10
Purchase #7	$61.28	5.661%	$64.7491	$64.75	$64.75	$64.70
7 purchase totals =	$953.25		$1,026.0156	$1,026.02	$1,026.00	$1,026.10