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	$81.77	5.543%	$86.3025	$86.30	$86.30	$86.30
Purchase #2	$182.63	4.747%	$191.2994	$191.30	$191.30	$191.30
Purchase #3	$250.40	6.129%	$265.747	$265.75	$265.75	$265.70
Purchase #4	$78.26	6.402%	$83.2702	$83.27	$83.25	$83.30
Purchase #5	$137.47	3.867%	$142.786	$142.79	$142.80	$142.80
Purchase #6	$151.47	10.477%	$167.3395	$167.34	$167.35	$167.30
Purchase #7	$141.42	5.638%	$149.3933	$149.39	$149.40	$149.40
7 purchase totals =	$1,023.42		$1,086.1379	$1,086.14	$1,086.15	$1,086.10