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	$176.61	12.545%	$198.7657	$198.77	$198.75	$198.80
Purchase #2	$203.55	6.714%	$217.2163	$217.22	$217.20	$217.20
Purchase #3	$171.33	11.222%	$190.5567	$190.56	$190.55	$190.60
Purchase #4	$227.81	12.271%	$255.7646	$255.76	$255.75	$255.80
Purchase #5	$37.83	9.688%	$41.495	$41.50	$41.50	$41.50
Purchase #6	$126.72	8.689%	$137.7307	$137.73	$137.75	$137.70
Purchase #7	$12.26	13.568%	$13.9234	$13.92	$13.90	$13.90
7 purchase totals =	$956.11		$1,055.4524	$1,055.46	$1,055.40	$1,055.50