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	$218.61	8.656%	$237.5329	$237.53	$237.55	$237.50
Purchase #2	$120.39	11.173%	$133.8412	$133.84	$133.85	$133.80
Purchase #3	$160.96	11.187%	$178.9666	$178.97	$178.95	$179.00
Purchase #4	$168.48	4.124%	$175.4281	$175.43	$175.45	$175.40
Purchase #5	$170.76	6.172%	$181.2993	$181.30	$181.30	$181.30
Purchase #6	$92.91	3.203%	$95.8859	$95.89	$95.90	$95.90
Purchase #7	$98.78	12.631%	$111.2569	$111.26	$111.25	$111.30
7 purchase totals =	$1,030.89		$1,114.2109	$1,114.22	$1,114.25	$1,114.20