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	$217.52	11.152%	$241.7778	$241.78	$241.80	$241.80
Purchase #2	$46.45	4.543%	$48.5602	$48.56	$48.55	$48.60
Purchase #3	$51.70	7.271%	$55.4591	$55.46	$55.45	$55.50
Purchase #4	$34.41	9.110%	$37.5448	$37.54	$37.55	$37.50
Purchase #5	$219.78	5.778%	$232.4789	$232.48	$232.50	$232.50
Purchase #6	$43.64	7.155%	$46.7624	$46.76	$46.75	$46.80
Purchase #7	$40.40	11.774%	$45.1567	$45.16	$45.15	$45.20
7 purchase totals =	$653.90		$707.7399	$707.74	$707.75	$707.90