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	$217.61	13.335%	$246.6283	$246.63	$246.65	$246.60
Purchase #2	$60.27	7.124%	$64.5636	$64.56	$64.55	$64.60
Purchase #3	$157.78	6.712%	$168.3702	$168.37	$168.35	$168.40
Purchase #4	$218.35	9.166%	$238.364	$238.36	$238.35	$238.40
Purchase #5	$200.53	8.763%	$218.1024	$218.10	$218.10	$218.10
Purchase #6	$169.52	8.814%	$184.4615	$184.46	$184.45	$184.50
Purchase #7	$27.86	13.118%	$31.5147	$31.51	$31.50	$31.50
7 purchase totals =	$1,051.92		$1,152.0047	$1,151.99	$1,151.95	$1,152.10