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	$69.82	3.546%	$72.2958	$72.30	$72.30	$72.30
Purchase #2	$114.50	11.395%	$127.5473	$127.55	$127.55	$127.50
Purchase #3	$165.98	13.826%	$188.9284	$188.93	$188.95	$188.90
Purchase #4	$174.43	7.511%	$187.5314	$187.53	$187.55	$187.50
Purchase #5	$196.62	11.490%	$219.2116	$219.21	$219.20	$219.20
Purchase #6	$93.95	12.441%	$105.6383	$105.64	$105.65	$105.60
Purchase #7	$105.40	7.623%	$113.4346	$113.43	$113.45	$113.40
7 purchase totals =	$920.70		$1,014.5874	$1,014.59	$1,014.65	$1,014.40