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	$98.37	3.394%	$101.7087	$101.71	$101.70	$101.70
Purchase #2	$150.43	3.307%	$155.4047	$155.40	$155.40	$155.40
Purchase #3	$179.54	3.534%	$185.8849	$185.88	$185.90	$185.90
Purchase #4	$216.31	3.709%	$224.3329	$224.33	$224.35	$224.30
Purchase #5	$115.84	8.819%	$126.0559	$126.06	$126.05	$126.10
Purchase #6	$138.27	4.776%	$144.8738	$144.87	$144.85	$144.90
Purchase #7	$122.51	11.483%	$136.5778	$136.58	$136.60	$136.60
7 purchase totals =	$1,021.27		$1,074.8387	$1,074.83	$1,074.85	$1,074.90