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	$63.55	13.186%	$71.9297	$71.93	$71.95	$71.90
Purchase #2	$40.80	13.710%	$46.3937	$46.39	$46.40	$46.40
Purchase #3	$144.38	8.219%	$156.2466	$156.25	$156.25	$156.20
Purchase #4	$181.54	10.459%	$200.5273	$200.53	$200.55	$200.50
Purchase #5	$219.46	7.369%	$235.632	$235.63	$235.65	$235.60
Purchase #6	$225.78	7.792%	$243.3728	$243.37	$243.35	$243.40
Purchase #7	$89.29	12.642%	$100.578	$100.58	$100.60	$100.60
7 purchase totals =	$964.80		$1,054.6801	$1,054.68	$1,054.75	$1,054.60