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	$49.96	4.747%	$52.3316	$52.33	$52.35	$52.30
Purchase #2	$214.61	5.799%	$227.0552	$227.06	$227.05	$227.10
Purchase #3	$133.42	4.482%	$139.3999	$139.40	$139.40	$139.40
Purchase #4	$235.72	6.696%	$251.5038	$251.50	$251.50	$251.50
Purchase #5	$35.66	5.233%	$37.5261	$37.53	$37.55	$37.50
Purchase #6	$143.33	6.545%	$152.7109	$152.71	$152.70	$152.70
Purchase #7	$215.79	11.849%	$241.359	$241.36	$241.35	$241.40
7 purchase totals =	$1,028.49		$1,101.8865	$1,101.89	$1,101.90	$1,101.90