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	$43.54	6.502%	$46.371	$46.37	$46.35	$46.40
Purchase #2	$221.41	7.490%	$237.9936	$237.99	$238.00	$238.00
Purchase #3	$87.83	11.834%	$98.2238	$98.22	$98.20	$98.20
Purchase #4	$125.33	3.158%	$129.2879	$129.29	$129.30	$129.30
Purchase #5	$133.31	12.568%	$150.0644	$150.06	$150.05	$150.10
Purchase #6	$146.31	12.450%	$164.5256	$164.53	$164.55	$164.50
Purchase #7	$214.59	3.864%	$222.8818	$222.88	$222.90	$222.90
7 purchase totals =	$972.32		$1,049.3481	$1,049.34	$1,049.35	$1,049.40