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	$181.65	8.186%	$196.5199	$196.52	$196.50	$196.50
Purchase #2	$152.73	12.627%	$172.0152	$172.02	$172.00	$172.00
Purchase #3	$145.67	11.538%	$162.4774	$162.48	$162.50	$162.50
Purchase #4	$109.83	13.311%	$124.4495	$124.45	$124.45	$124.40
Purchase #5	$186.39	12.336%	$209.3831	$209.38	$209.40	$209.40
Purchase #6	$204.75	7.636%	$220.3847	$220.38	$220.40	$220.40
Purchase #7	$183.60	9.557%	$201.1467	$201.15	$201.15	$201.10
7 purchase totals =	$1,164.62		$1,286.3765	$1,286.38	$1,286.40	$1,286.30