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	$167.44	4.406%	$174.8174	$174.82	$174.80	$174.80
Purchase #2	$74.86	4.665%	$78.3522	$78.35	$78.35	$78.40
Purchase #3	$191.63	4.773%	$200.7765	$200.78	$200.80	$200.80
Purchase #4	$56.59	8.257%	$61.2626	$61.26	$61.25	$61.30
Purchase #5	$148.44	6.775%	$158.4968	$158.50	$158.50	$158.50
Purchase #6	$178.74	5.391%	$188.3759	$188.38	$188.40	$188.40
Purchase #7	$246.39	6.296%	$261.9027	$261.90	$261.90	$261.90
7 purchase totals =	$1,064.09		$1,123.9841	$1,123.99	$1,124.00	$1,124.10