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	$216.65	3.867%	$225.0279	$225.03	$225.05	$225.00
Purchase #2	$67.31	6.154%	$71.4523	$71.45	$71.45	$71.50
Purchase #3	$186.95	12.689%	$210.6721	$210.67	$210.65	$210.70
Purchase #4	$234.53	4.318%	$244.657	$244.66	$244.65	$244.70
Purchase #5	$231.43	10.512%	$255.7579	$255.76	$255.75	$255.80
Purchase #6	$160.62	12.107%	$180.0663	$180.07	$180.05	$180.10
Purchase #7	$190.43	3.316%	$196.7447	$196.74	$196.75	$196.70
7 purchase totals =	$1,287.92		$1,384.3782	$1,384.38	$1,384.35	$1,384.50