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	$43.36	6.433%	$46.1493	$46.15	$46.15	$46.10
Purchase #2	$97.43	6.108%	$103.381	$103.38	$103.40	$103.40
Purchase #3	$174.85	12.217%	$196.2114	$196.21	$196.20	$196.20
Purchase #4	$154.56	11.145%	$171.7857	$171.79	$171.80	$171.80
Purchase #5	$87.54	12.143%	$98.17	$98.17	$98.15	$98.20
Purchase #6	$138.27	3.120%	$142.584	$142.58	$142.60	$142.60
Purchase #7	$168.70	10.196%	$185.9007	$185.90	$185.90	$185.90
7 purchase totals =	$864.71		$944.1821	$944.18	$944.20	$944.20