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	$46.25	6.452%	$49.2341	$49.23	$49.25	$49.20
Purchase #2	$114.89	13.126%	$129.9705	$129.97	$129.95	$130.00
Purchase #3	$250.44	8.724%	$272.2884	$272.29	$272.30	$272.30
Purchase #4	$177.90	6.172%	$188.88	$188.88	$188.90	$188.90
Purchase #5	$164.47	12.220%	$184.5682	$184.57	$184.55	$184.60
Purchase #6	$50.38	3.874%	$52.3317	$52.33	$52.35	$52.30
Purchase #7	$219.72	6.393%	$233.7667	$233.77	$233.75	$233.80
7 purchase totals =	$1,024.05		$1,111.0396	$1,111.04	$1,111.05	$1,111.10