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	$180.87	9.215%	$197.5372	$197.54	$197.55	$197.50
Purchase #2	$220.86	4.301%	$230.3592	$230.36	$230.35	$230.40
Purchase #3	$57.39	4.210%	$59.8061	$59.81	$59.80	$59.80
Purchase #4	$58.25	6.675%	$62.1382	$62.14	$62.15	$62.10
Purchase #5	$85.98	4.106%	$89.5103	$89.51	$89.50	$89.50
Purchase #6	$238.93	11.768%	$267.0473	$267.05	$267.05	$267.00
Purchase #7	$136.27	8.146%	$147.3706	$147.37	$147.35	$147.40
7 purchase totals =	$978.55		$1,053.7689	$1,053.78	$1,053.75	$1,053.70