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	$191.59	10.265%	$211.2567	$211.26	$211.25	$211.30
Purchase #2	$162.59	12.389%	$182.7333	$182.73	$182.75	$182.70
Purchase #3	$56.63	8.197%	$61.272	$61.27	$61.25	$61.30
Purchase #4	$199.26	13.329%	$225.8194	$225.82	$225.80	$225.80
Purchase #5	$71.48	12.673%	$80.5387	$80.54	$80.55	$80.50
Purchase #6	$32.74	7.752%	$35.278	$35.28	$35.30	$35.30
Purchase #7	$241.33	8.796%	$262.5574	$262.56	$262.55	$262.60
7 purchase totals =	$955.62		$1,059.4555	$1,059.46	$1,059.45	$1,059.50