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	$162.29	5.568%	$171.3263	$171.33	$171.35	$171.30
Purchase #2	$32.30	8.304%	$34.9822	$34.98	$35.00	$35.00
Purchase #3	$35.55	7.234%	$38.1217	$38.12	$38.10	$38.10
Purchase #4	$78.37	6.617%	$83.5557	$83.56	$83.55	$83.60
Purchase #5	$45.38	8.231%	$49.1152	$49.12	$49.10	$49.10
Purchase #6	$177.63	10.350%	$196.0147	$196.01	$196.00	$196.00
Purchase #7	$228.86	6.818%	$244.4637	$244.46	$244.45	$244.50
7 purchase totals =	$760.38		$817.5795	$817.58	$817.55	$817.60