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	$49.30	10.775%	$54.6121	$54.61	$54.60	$54.60
Purchase #2	$242.25	12.684%	$272.977	$272.98	$273.00	$273.00
Purchase #3	$177.58	10.765%	$196.6965	$196.70	$196.70	$196.70
Purchase #4	$103.56	13.179%	$117.2082	$117.21	$117.20	$117.20
Purchase #5	$160.77	4.398%	$167.8407	$167.84	$167.85	$167.80
Purchase #6	$6.78	5.427%	$7.148	$7.15	$7.15	$7.10
Purchase #7	$206.67	4.565%	$216.1045	$216.10	$216.10	$216.10
7 purchase totals =	$946.91		$1,032.5870	$1,032.59	$1,032.60	$1,032.50