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	$44.78	4.607%	$46.843	$46.84	$46.85	$46.80
Purchase #2	$112.42	13.202%	$127.2617	$127.26	$127.25	$127.30
Purchase #3	$102.31	9.857%	$112.3947	$112.39	$112.40	$112.40
Purchase #4	$33.88	4.566%	$35.427	$35.43	$35.45	$35.40
Purchase #5	$215.91	3.398%	$223.2466	$223.25	$223.25	$223.20
Purchase #6	$183.80	9.287%	$200.8695	$200.87	$200.85	$200.90
Purchase #7	$170.88	4.760%	$179.0139	$179.01	$179.00	$179.00
7 purchase totals =	$863.98		$925.0564	$925.05	$925.05	$925.00