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	$196.85	9.232%	$215.0232	$215.02	$215.00	$215.00
Purchase #2	$99.33	3.597%	$102.9029	$102.90	$102.90	$102.90
Purchase #3	$213.50	4.108%	$222.2706	$222.27	$222.25	$222.30
Purchase #4	$173.29	3.769%	$179.8213	$179.82	$179.80	$179.80
Purchase #5	$148.63	10.264%	$163.8854	$163.89	$163.90	$163.90
Purchase #6	$238.89	4.773%	$250.2922	$250.29	$250.30	$250.30
Purchase #7	$215.73	13.601%	$245.0714	$245.07	$245.05	$245.10
7 purchase totals =	$1,286.22		$1,379.2670	$1,379.26	$1,379.20	$1,379.30