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	$196.25	4.759%	$205.5895	$205.59	$205.60	$205.60
Purchase #2	$125.85	11.852%	$140.7657	$140.77	$140.75	$140.80
Purchase #3	$206.31	11.127%	$229.2661	$229.27	$229.25	$229.30
Purchase #4	$131.85	7.514%	$141.7572	$141.76	$141.75	$141.80
Purchase #5	$50.44	12.164%	$56.5755	$56.58	$56.60	$56.60
Purchase #6	$181.94	8.518%	$197.4376	$197.44	$197.45	$197.40
Purchase #7	$44.90	3.354%	$46.4059	$46.41	$46.40	$46.40
7 purchase totals =	$937.54		$1,017.7975	$1,017.82	$1,017.80	$1,017.90