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	$35.85	3.436%	$37.0818	$37.08	$37.10	$37.10
Purchase #2	$6.77	7.372%	$7.2691	$7.27	$7.25	$7.30
Purchase #3	$243.95	10.605%	$269.8209	$269.82	$269.80	$269.80
Purchase #4	$24.32	3.456%	$25.1605	$25.16	$25.15	$25.20
Purchase #5	$10.33	13.369%	$11.711	$11.71	$11.70	$11.70
Purchase #6	$139.59	5.639%	$147.4615	$147.46	$147.45	$147.50
Purchase #7	$247.96	10.444%	$273.8569	$273.86	$273.85	$273.90
7 purchase totals =	$708.77		$772.3617	$772.36	$772.30	$772.50