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	$241.81	8.243%	$261.7424	$261.74	$261.75	$261.70
Purchase #2	$161.53	4.868%	$169.3933	$169.39	$169.40	$169.40
Purchase #3	$28.42	9.594%	$31.1466	$31.15	$31.15	$31.10
Purchase #4	$66.45	8.265%	$71.9421	$71.94	$71.95	$71.90
Purchase #5	$60.42	7.496%	$64.9491	$64.95	$64.95	$64.90
Purchase #6	$248.46	13.829%	$282.8195	$282.82	$282.80	$282.80
Purchase #7	$150.85	9.200%	$164.7282	$164.73	$164.75	$164.70
7 purchase totals =	$957.94		$1,046.7212	$1,046.72	$1,046.75	$1,046.50