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	$43.78	4.681%	$45.8293	$45.83	$45.85	$45.80
Purchase #2	$28.78	13.226%	$32.5864	$32.59	$32.60	$32.60
Purchase #3	$162.56	8.181%	$175.859	$175.86	$175.85	$175.90
Purchase #4	$240.48	13.550%	$273.065	$273.07	$273.05	$273.10
Purchase #5	$226.52	11.210%	$251.9129	$251.91	$251.90	$251.90
Purchase #6	$162.58	3.570%	$168.3841	$168.38	$168.40	$168.40
Purchase #7	$115.33	3.323%	$119.1624	$119.16	$119.15	$119.20
7 purchase totals =	$980.03		$1,066.7991	$1,066.80	$1,066.80	$1,066.90