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	$167.98	8.833%	$182.8177	$182.82	$182.80	$182.80
Purchase #2	$166.46	3.662%	$172.5558	$172.56	$172.55	$172.60
Purchase #3	$35.70	10.543%	$39.4639	$39.46	$39.45	$39.50
Purchase #4	$82.68	7.122%	$88.5685	$88.57	$88.55	$88.60
Purchase #5	$160.83	4.484%	$168.0416	$168.04	$168.05	$168.00
Purchase #6	$210.58	10.282%	$232.2318	$232.23	$232.25	$232.20
Purchase #7	$138.27	6.578%	$147.3654	$147.37	$147.35	$147.40
7 purchase totals =	$962.50		$1,031.0447	$1,031.05	$1,031.00	$1,031.10