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	$198.86	12.108%	$222.938	$222.94	$222.95	$222.90
Purchase #2	$29.32	4.270%	$30.572	$30.57	$30.55	$30.60
Purchase #3	$76.69	3.223%	$79.1617	$79.16	$79.15	$79.20
Purchase #4	$38.39	12.779%	$43.2959	$43.30	$43.30	$43.30
Purchase #5	$240.49	12.526%	$270.6138	$270.61	$270.60	$270.60
Purchase #6	$89.83	9.775%	$98.6109	$98.61	$98.60	$98.60
Purchase #7	$185.45	13.557%	$210.5915	$210.59	$210.60	$210.60
7 purchase totals =	$859.03		$955.7838	$955.78	$955.75	$955.80