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	$149.57	11.752%	$167.1475	$167.15	$167.15	$167.10
Purchase #2	$7.39	13.510%	$8.3884	$8.39	$8.40	$8.40
Purchase #3	$47.31	4.315%	$49.3514	$49.35	$49.35	$49.40
Purchase #4	$34.46	9.631%	$37.7788	$37.78	$37.80	$37.80
Purchase #5	$145.63	7.443%	$156.4692	$156.47	$156.45	$156.50
Purchase #6	$62.94	10.663%	$69.6513	$69.65	$69.65	$69.70
Purchase #7	$105.43	12.611%	$118.7258	$118.73	$118.75	$118.70
7 purchase totals =	$552.73		$607.5124	$607.52	$607.55	$607.60