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	$69.42	10.111%	$76.4391	$76.44	$76.45	$76.40
Purchase #2	$46.83	5.853%	$49.571	$49.57	$49.55	$49.60
Purchase #3	$242.58	9.560%	$265.7706	$265.77	$265.75	$265.80
Purchase #4	$139.76	9.149%	$152.5466	$152.55	$152.55	$152.50
Purchase #5	$244.89	6.143%	$259.9336	$259.93	$259.95	$259.90
Purchase #6	$234.90	6.483%	$250.1286	$250.13	$250.15	$250.10
Purchase #7	$134.91	5.477%	$142.299	$142.30	$142.30	$142.30
7 purchase totals =	$1,113.29		$1,196.6885	$1,196.69	$1,196.70	$1,196.60