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	$194.69	10.292%	$214.7275	$214.73	$214.75	$214.70
Purchase #2	$143.63	4.759%	$150.4654	$150.47	$150.45	$150.50
Purchase #3	$245.71	13.765%	$279.532	$279.53	$279.55	$279.50
Purchase #4	$72.71	8.293%	$78.7398	$78.74	$78.75	$78.70
Purchase #5	$186.63	7.169%	$200.0095	$200.01	$200.00	$200.00
Purchase #6	$198.43	5.290%	$208.9269	$208.93	$208.95	$208.90
Purchase #7	$47.94	11.362%	$53.3869	$53.39	$53.40	$53.40
7 purchase totals =	$1,089.74		$1,185.7880	$1,185.80	$1,185.85	$1,185.70