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	$87.63	8.103%	$94.7307	$94.73	$94.75	$94.70
Purchase #2	$167.90	4.172%	$174.9048	$174.90	$174.90	$174.90
Purchase #3	$12.89	3.256%	$13.3097	$13.31	$13.30	$13.30
Purchase #4	$26.69	4.364%	$27.8548	$27.85	$27.85	$27.90
Purchase #5	$77.73	9.641%	$85.2239	$85.22	$85.20	$85.20
Purchase #6	$6.31	3.465%	$6.5286	$6.53	$6.55	$6.50
Purchase #7	$119.31	4.404%	$124.5644	$124.56	$124.55	$124.60
7 purchase totals =	$498.46		$527.1169	$527.10	$527.10	$527.10