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	$127.27	11.443%	$141.8335	$141.83	$141.85	$141.80
Purchase #2	$55.43	11.444%	$61.7734	$61.77	$61.75	$61.80
Purchase #3	$159.54	5.246%	$167.9095	$167.91	$167.90	$167.90
Purchase #4	$168.28	5.201%	$177.0322	$177.03	$177.05	$177.00
Purchase #5	$100.89	5.695%	$106.6357	$106.64	$106.65	$106.60
Purchase #6	$60.58	5.195%	$63.7271	$63.73	$63.75	$63.70
Purchase #7	$134.83	5.601%	$142.3818	$142.38	$142.40	$142.40
7 purchase totals =	$806.82		$861.2932	$861.29	$861.35	$861.20