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	$147.71	5.571%	$155.9389	$155.94	$155.95	$155.90
Purchase #2	$134.90	13.355%	$152.9159	$152.92	$152.90	$152.90
Purchase #3	$154.69	8.533%	$167.8897	$167.89	$167.90	$167.90
Purchase #4	$174.56	12.824%	$196.9456	$196.95	$196.95	$196.90
Purchase #5	$42.88	9.243%	$46.8434	$46.84	$46.85	$46.80
Purchase #6	$188.53	6.861%	$201.465	$201.47	$201.45	$201.50
Purchase #7	$231.62	5.587%	$244.5606	$244.56	$244.55	$244.60
7 purchase totals =	$1,074.89		$1,166.5591	$1,166.57	$1,166.55	$1,166.50