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	$118.44	9.735%	$129.9701	$129.97	$129.95	$130.00
Purchase #2	$32.65	13.807%	$37.158	$37.16	$37.15	$37.20
Purchase #3	$187.67	4.691%	$196.4736	$196.47	$196.45	$196.50
Purchase #4	$228.82	10.625%	$253.1321	$253.13	$253.15	$253.10
Purchase #5	$214.56	9.689%	$235.3487	$235.35	$235.35	$235.30
Purchase #6	$90.44	13.213%	$102.3898	$102.39	$102.40	$102.40
Purchase #7	$116.56	3.279%	$120.382	$120.38	$120.40	$120.40
7 purchase totals =	$989.14		$1,074.8543	$1,074.85	$1,074.85	$1,074.90