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	$59.38	3.102%	$61.222	$61.22	$61.20	$61.20
Purchase #2	$184.83	3.349%	$191.02	$191.02	$191.00	$191.00
Purchase #3	$249.69	12.832%	$281.7302	$281.73	$281.75	$281.70
Purchase #4	$73.28	11.672%	$81.8332	$81.83	$81.85	$81.80
Purchase #5	$108.90	3.290%	$112.4828	$112.48	$112.50	$112.50
Purchase #6	$174.59	5.444%	$184.0947	$184.09	$184.10	$184.10
Purchase #7	$137.48	3.776%	$142.6712	$142.67	$142.65	$142.70
7 purchase totals =	$988.15		$1,055.0541	$1,055.04	$1,055.05	$1,055.00