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	$122.86	5.763%	$129.9404	$129.94	$129.95	$129.90
Purchase #2	$28.98	6.783%	$30.9457	$30.95	$30.95	$30.90
Purchase #3	$26.29	3.386%	$27.1802	$27.18	$27.20	$27.20
Purchase #4	$118.34	11.444%	$131.8828	$131.88	$131.90	$131.90
Purchase #5	$68.46	3.140%	$70.6096	$70.61	$70.60	$70.60
Purchase #6	$9.52	7.727%	$10.2556	$10.26	$10.25	$10.30
Purchase #7	$38.96	9.471%	$42.6499	$42.65	$42.65	$42.60
7 purchase totals =	$413.41		$443.4642	$443.47	$443.50	$443.40