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	$208.41	9.387%	$227.9734	$227.97	$227.95	$228.00
Purchase #2	$155.86	7.561%	$167.6446	$167.64	$167.65	$167.60
Purchase #3	$30.80	5.713%	$32.5596	$32.56	$32.55	$32.60
Purchase #4	$92.94	8.615%	$100.9468	$100.95	$100.95	$100.90
Purchase #5	$31.65	10.601%	$35.0052	$35.01	$35.00	$35.00
Purchase #6	$232.56	9.106%	$253.7369	$253.74	$253.75	$253.70
Purchase #7	$182.37	4.828%	$191.1748	$191.17	$191.15	$191.20
7 purchase totals =	$934.59		$1,009.0413	$1,009.04	$1,009.00	$1,009.00