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	$84.99	11.829%	$95.0435	$95.04	$95.05	$95.00
Purchase #2	$19.33	5.864%	$20.4635	$20.46	$20.45	$20.50
Purchase #3	$81.73	10.770%	$90.5323	$90.53	$90.55	$90.50
Purchase #4	$246.51	7.658%	$265.3877	$265.39	$265.40	$265.40
Purchase #5	$135.30	6.688%	$144.3489	$144.35	$144.35	$144.30
Purchase #6	$39.31	6.156%	$41.7299	$41.73	$41.75	$41.70
Purchase #7	$217.78	5.382%	$229.5009	$229.50	$229.50	$229.50
7 purchase totals =	$824.95		$887.0067	$887.00	$887.05	$886.90