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	$89.46	6.227%	$95.0307	$95.03	$95.05	$95.00
Purchase #2	$41.55	8.189%	$44.9525	$44.95	$44.95	$45.00
Purchase #3	$142.31	5.690%	$150.4074	$150.41	$150.40	$150.40
Purchase #4	$76.82	11.763%	$85.8563	$85.86	$85.85	$85.90
Purchase #5	$176.90	8.444%	$191.8374	$191.84	$191.85	$191.80
Purchase #6	$72.75	3.309%	$75.1573	$75.16	$75.15	$75.20
Purchase #7	$171.82	7.271%	$184.313	$184.31	$184.30	$184.30
7 purchase totals =	$771.61		$827.5546	$827.56	$827.55	$827.60