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	$165.42	8.415%	$179.3401	$179.34	$179.35	$179.30
Purchase #2	$134.38	4.434%	$140.3384	$140.34	$140.35	$140.30
Purchase #3	$119.40	6.146%	$126.7383	$126.74	$126.75	$126.70
Purchase #4	$131.65	4.296%	$137.3057	$137.31	$137.30	$137.30
Purchase #5	$141.34	6.341%	$150.3024	$150.30	$150.30	$150.30
Purchase #6	$106.52	10.597%	$117.8079	$117.81	$117.80	$117.80
Purchase #7	$188.81	4.127%	$196.6022	$196.60	$196.60	$196.60
7 purchase totals =	$987.52		$1,048.4350	$1,048.44	$1,048.45	$1,048.30