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	$200.42	13.497%	$227.4707	$227.47	$227.45	$227.50
Purchase #2	$105.58	3.472%	$109.2457	$109.25	$109.25	$109.20
Purchase #3	$202.65	6.339%	$215.496	$215.50	$215.50	$215.50
Purchase #4	$127.36	13.480%	$144.5281	$144.53	$144.55	$144.50
Purchase #5	$250.28	7.751%	$269.6792	$269.68	$269.70	$269.70
Purchase #6	$55.78	6.238%	$59.2596	$59.26	$59.25	$59.30
Purchase #7	$20.65	6.817%	$22.0577	$22.06	$22.05	$22.10
7 purchase totals =	$962.72		$1,047.7370	$1,047.75	$1,047.75	$1,047.80