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	$90.58	5.562%	$95.6181	$95.62	$95.60	$95.60
Purchase #2	$68.57	4.669%	$71.7715	$71.77	$71.75	$71.80
Purchase #3	$180.95	5.740%	$191.3365	$191.34	$191.35	$191.30
Purchase #4	$182.83	4.617%	$191.2713	$191.27	$191.25	$191.30
Purchase #5	$201.67	5.256%	$212.2698	$212.27	$212.25	$212.30
Purchase #6	$135.63	6.436%	$144.3591	$144.36	$144.35	$144.40
Purchase #7	$108.54	13.541%	$123.2374	$123.24	$123.25	$123.20
7 purchase totals =	$968.77		$1,029.8637	$1,029.87	$1,029.80	$1,029.90