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	$150.41	12.711%	$169.5286	$169.53	$169.55	$169.50
Purchase #2	$186.65	9.364%	$204.1279	$204.13	$204.15	$204.10
Purchase #3	$71.85	9.602%	$78.749	$78.75	$78.75	$78.70
Purchase #4	$122.69	3.615%	$127.1252	$127.13	$127.15	$127.10
Purchase #5	$101.52	13.153%	$114.8729	$114.87	$114.85	$114.90
Purchase #6	$11.79	4.511%	$12.3218	$12.32	$12.30	$12.30
Purchase #7	$214.85	13.242%	$243.3004	$243.30	$243.30	$243.30
7 purchase totals =	$859.76		$950.0258	$950.03	$950.05	$949.90