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	$169.47	10.819%	$187.805	$187.81	$187.80	$187.80
Purchase #2	$243.94	4.865%	$255.8077	$255.81	$255.80	$255.80
Purchase #3	$31.32	3.180%	$32.316	$32.32	$32.30	$32.30
Purchase #4	$161.67	4.303%	$168.6267	$168.63	$168.65	$168.60
Purchase #5	$230.64	13.336%	$261.3982	$261.40	$261.40	$261.40
Purchase #6	$183.85	4.830%	$192.73	$192.73	$192.75	$192.70
Purchase #7	$161.70	3.561%	$167.4581	$167.46	$167.45	$167.50
7 purchase totals =	$1,182.59		$1,266.1417	$1,266.16	$1,266.15	$1,266.10