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	$89.93	5.780%	$95.128	$95.13	$95.15	$95.10
Purchase #2	$158.40	4.213%	$165.0734	$165.07	$165.05	$165.10
Purchase #3	$176.98	4.230%	$184.4663	$184.47	$184.45	$184.50
Purchase #4	$47.86	9.661%	$52.4838	$52.48	$52.50	$52.50
Purchase #5	$239.88	13.612%	$272.5325	$272.53	$272.55	$272.50
Purchase #6	$181.61	7.602%	$195.416	$195.42	$195.40	$195.40
Purchase #7	$29.80	6.442%	$31.7197	$31.72	$31.70	$31.70
7 purchase totals =	$924.46		$996.8197	$996.82	$996.80	$996.80