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	$154.51	5.127%	$162.4317	$162.43	$162.45	$162.40
Purchase #2	$119.52	3.674%	$123.9112	$123.91	$123.90	$123.90
Purchase #3	$65.28	10.188%	$71.9307	$71.93	$71.95	$71.90
Purchase #4	$147.97	7.414%	$158.9405	$158.94	$158.95	$158.90
Purchase #5	$76.57	12.635%	$86.2446	$86.24	$86.25	$86.20
Purchase #6	$133.57	9.319%	$146.0174	$146.02	$146.00	$146.00
Purchase #7	$243.82	4.595%	$255.0235	$255.02	$255.00	$255.00
7 purchase totals =	$941.24		$1,004.4996	$1,004.49	$1,004.50	$1,004.30