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	$174.43	3.237%	$180.0763	$180.08	$180.10	$180.10
Purchase #2	$169.61	10.278%	$187.0425	$187.04	$187.05	$187.00
Purchase #3	$226.35	6.544%	$241.1623	$241.16	$241.15	$241.20
Purchase #4	$59.54	4.118%	$61.9919	$61.99	$62.00	$62.00
Purchase #5	$146.86	12.402%	$165.0736	$165.07	$165.05	$165.10
Purchase #6	$13.39	12.799%	$15.1038	$15.10	$15.10	$15.10
Purchase #7	$189.42	3.699%	$196.4266	$196.43	$196.45	$196.40
7 purchase totals =	$979.60		$1,046.8770	$1,046.87	$1,046.90	$1,046.90