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	$164.28	9.299%	$179.5564	$179.56	$179.55	$179.60
Purchase #2	$184.25	6.415%	$196.0696	$196.07	$196.05	$196.10
Purchase #3	$97.68	3.326%	$100.9288	$100.93	$100.95	$100.90
Purchase #4	$127.31	11.570%	$142.0398	$142.04	$142.05	$142.00
Purchase #5	$184.41	8.161%	$199.4597	$199.46	$199.45	$199.50
Purchase #6	$181.39	9.726%	$199.032	$199.03	$199.05	$199.00
Purchase #7	$58.94	11.310%	$65.6061	$65.61	$65.60	$65.60
7 purchase totals =	$998.26		$1,082.6924	$1,082.70	$1,082.70	$1,082.70