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	$112.71	5.550%	$118.9654	$118.97	$118.95	$119.00
Purchase #2	$48.56	4.231%	$50.6146	$50.61	$50.60	$50.60
Purchase #3	$35.29	7.478%	$37.929	$37.93	$37.95	$37.90
Purchase #4	$217.73	7.867%	$234.8588	$234.86	$234.85	$234.90
Purchase #5	$238.38	11.537%	$265.8819	$265.88	$265.90	$265.90
Purchase #6	$167.78	11.518%	$187.1049	$187.10	$187.10	$187.10
Purchase #7	$44.84	5.704%	$47.3977	$47.40	$47.40	$47.40
7 purchase totals =	$865.29		$942.7523	$942.75	$942.75	$942.80