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	$125.30	6.764%	$133.7753	$133.78	$133.80	$133.80
Purchase #2	$74.43	4.139%	$77.5107	$77.51	$77.50	$77.50
Purchase #3	$77.85	9.661%	$85.3711	$85.37	$85.35	$85.40
Purchase #4	$156.70	6.604%	$167.0485	$167.05	$167.05	$167.00
Purchase #5	$31.93	3.551%	$33.0638	$33.06	$33.05	$33.10
Purchase #6	$239.45	8.360%	$259.468	$259.47	$259.45	$259.50
Purchase #7	$225.45	13.462%	$255.8001	$255.80	$255.80	$255.80
7 purchase totals =	$931.11		$1,012.0375	$1,012.04	$1,012.00	$1,012.10