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	$60.34	3.471%	$62.4344	$62.43	$62.45	$62.40
Purchase #2	$126.95	5.715%	$134.2052	$134.21	$134.20	$134.20
Purchase #3	$229.67	6.410%	$244.3918	$244.39	$244.40	$244.40
Purchase #4	$153.59	7.523%	$165.1446	$165.14	$165.15	$165.10
Purchase #5	$109.91	3.788%	$114.0734	$114.07	$114.05	$114.10
Purchase #6	$152.47	9.723%	$167.2947	$167.29	$167.30	$167.30
Purchase #7	$239.59	7.188%	$256.8117	$256.81	$256.80	$256.80
7 purchase totals =	$1,072.52		$1,144.3558	$1,144.34	$1,144.35	$1,144.30