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	$125.67	3.342%	$129.8699	$129.87	$129.85	$129.90
Purchase #2	$141.43	7.781%	$152.4347	$152.43	$152.45	$152.40
Purchase #3	$8.43	11.382%	$9.3895	$9.39	$9.40	$9.40
Purchase #4	$81.46	5.698%	$86.1016	$86.10	$86.10	$86.10
Purchase #5	$55.27	6.848%	$59.0549	$59.05	$59.05	$59.10
Purchase #6	$113.71	4.693%	$119.0464	$119.05	$119.05	$119.00
Purchase #7	$47.96	11.322%	$53.39	$53.39	$53.40	$53.40
7 purchase totals =	$573.93		$609.2870	$609.28	$609.30	$609.30