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	$89.82	5.779%	$95.0107	$95.01	$95.00	$95.00
Purchase #2	$102.90	4.129%	$107.1487	$107.15	$107.15	$107.10
Purchase #3	$48.65	3.644%	$50.4228	$50.42	$50.40	$50.40
Purchase #4	$216.46	4.415%	$226.0167	$226.02	$226.00	$226.00
Purchase #5	$99.28	9.839%	$109.0482	$109.05	$109.05	$109.00
Purchase #6	$109.96	6.856%	$117.4989	$117.50	$117.50	$117.50
Purchase #7	$85.28	6.636%	$90.9392	$90.94	$90.95	$90.90
7 purchase totals =	$752.35		$796.0852	$796.09	$796.05	$795.90