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	$219.55	7.846%	$236.7759	$236.78	$236.80	$236.80
Purchase #2	$19.25	7.817%	$20.7548	$20.75	$20.75	$20.80
Purchase #3	$203.25	6.473%	$216.4064	$216.41	$216.40	$216.40
Purchase #4	$237.37	3.758%	$246.2904	$246.29	$246.30	$246.30
Purchase #5	$6.87	13.873%	$7.8231	$7.82	$7.80	$7.80
Purchase #6	$174.94	7.700%	$188.4104	$188.41	$188.40	$188.40
Purchase #7	$178.44	9.867%	$196.0467	$196.05	$196.05	$196.00
7 purchase totals =	$1,039.67		$1,112.5077	$1,112.51	$1,112.50	$1,112.50