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	$235.49	4.435%	$245.934	$245.93	$245.95	$245.90
Purchase #2	$173.93	7.699%	$187.3209	$187.32	$187.30	$187.30
Purchase #3	$24.61	12.781%	$27.7554	$27.76	$27.75	$27.80
Purchase #4	$209.36	3.749%	$217.2089	$217.21	$217.20	$217.20
Purchase #5	$94.91	3.557%	$98.2859	$98.29	$98.30	$98.30
Purchase #6	$178.69	3.821%	$185.5177	$185.52	$185.50	$185.50
Purchase #7	$138.43	3.197%	$142.8556	$142.86	$142.85	$142.90
7 purchase totals =	$1,055.42		$1,104.8784	$1,104.89	$1,104.85	$1,104.90