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	$196.42	4.340%	$204.9446	$204.94	$204.95	$204.90
Purchase #2	$46.92	7.636%	$50.5028	$50.50	$50.50	$50.50
Purchase #3	$6.70	11.356%	$7.4609	$7.46	$7.45	$7.50
Purchase #4	$85.93	7.429%	$92.3137	$92.31	$92.30	$92.30
Purchase #5	$239.90	11.192%	$266.7496	$266.75	$266.75	$266.70
Purchase #6	$154.37	6.751%	$164.7915	$164.79	$164.80	$164.80
Purchase #7	$36.54	3.843%	$37.9442	$37.94	$37.95	$37.90
7 purchase totals =	$766.78		$824.7073	$824.69	$824.70	$824.60