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	$54.92	13.528%	$62.3496	$62.35	$62.35	$62.30
Purchase #2	$130.74	5.120%	$137.4339	$137.43	$137.45	$137.40
Purchase #3	$175.41	3.248%	$181.1073	$181.11	$181.10	$181.10
Purchase #4	$152.76	9.522%	$167.3058	$167.31	$167.30	$167.30
Purchase #5	$28.57	13.749%	$32.4981	$32.50	$32.50	$32.50
Purchase #6	$136.65	4.290%	$142.5123	$142.51	$142.50	$142.50
Purchase #7	$56.86	11.478%	$63.3864	$63.39	$63.40	$63.40
7 purchase totals =	$735.91		$786.5934	$786.60	$786.60	$786.50