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	$194.86	10.202%	$214.7396	$214.74	$214.75	$214.70
Purchase #2	$118.73	13.131%	$134.3204	$134.32	$134.30	$134.30
Purchase #3	$47.89	9.530%	$52.4539	$52.45	$52.45	$52.50
Purchase #4	$228.47	3.639%	$236.784	$236.78	$236.80	$236.80
Purchase #5	$133.82	5.482%	$141.156	$141.16	$141.15	$141.20
Purchase #6	$162.93	13.610%	$185.1048	$185.10	$185.10	$185.10
Purchase #7	$199.71	13.611%	$226.8925	$226.89	$226.90	$226.90
7 purchase totals =	$1,086.41		$1,191.4512	$1,191.44	$1,191.45	$1,191.50