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	$194.47	11.287%	$216.4198	$216.42	$216.40	$216.40
Purchase #2	$149.48	12.307%	$167.8765	$167.88	$167.90	$167.90
Purchase #3	$47.49	6.615%	$50.6315	$50.63	$50.65	$50.60
Purchase #4	$42.49	7.381%	$45.6262	$45.63	$45.65	$45.60
Purchase #5	$113.89	11.257%	$126.7106	$126.71	$126.70	$126.70
Purchase #6	$234.53	13.254%	$265.6146	$265.61	$265.60	$265.60
Purchase #7	$160.28	12.109%	$179.6883	$179.69	$179.70	$179.70
7 purchase totals =	$942.63		$1,052.5675	$1,052.57	$1,052.60	$1,052.50