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	$173.62	11.529%	$193.6366	$193.64	$193.65	$193.60
Purchase #2	$88.85	13.250%	$100.6226	$100.62	$100.60	$100.60
Purchase #3	$89.40	9.677%	$98.0512	$98.05	$98.05	$98.10
Purchase #4	$186.92	6.303%	$198.7016	$198.70	$198.70	$198.70
Purchase #5	$131.86	12.586%	$148.4559	$148.46	$148.45	$148.50
Purchase #6	$203.50	5.850%	$215.4048	$215.40	$215.40	$215.40
Purchase #7	$113.52	13.240%	$128.55	$128.55	$128.55	$128.60
7 purchase totals =	$987.67		$1,083.4227	$1,083.42	$1,083.40	$1,083.50