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	$145.48	4.622%	$152.2041	$152.20	$152.20	$152.20
Purchase #2	$12.27	3.790%	$12.735	$12.74	$12.75	$12.70
Purchase #3	$206.25	7.740%	$222.2138	$222.21	$222.20	$222.20
Purchase #4	$184.80	10.171%	$203.596	$203.60	$203.60	$203.60
Purchase #5	$145.91	13.641%	$165.8136	$165.81	$165.80	$165.80
Purchase #6	$226.51	12.757%	$255.4059	$255.41	$255.40	$255.40
Purchase #7	$210.46	5.470%	$221.9722	$221.97	$221.95	$222.00
7 purchase totals =	$1,131.68		$1,233.9406	$1,233.94	$1,233.90	$1,233.90