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	$196.30	11.493%	$218.8608	$218.86	$218.85	$218.90
Purchase #2	$67.63	10.373%	$74.6453	$74.65	$74.65	$74.60
Purchase #3	$6.99	7.241%	$7.4961	$7.50	$7.50	$7.50
Purchase #4	$36.51	4.415%	$38.1219	$38.12	$38.10	$38.10
Purchase #5	$79.52	11.261%	$88.4747	$88.47	$88.45	$88.50
Purchase #6	$172.61	7.673%	$185.8544	$185.85	$185.85	$185.90
Purchase #7	$124.72	5.266%	$131.2878	$131.29	$131.30	$131.30
7 purchase totals =	$684.28		$744.7410	$744.74	$744.70	$744.80