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	$152.75	6.143%	$162.1334	$162.13	$162.15	$162.10
Purchase #2	$207.85	8.103%	$224.6921	$224.69	$224.70	$224.70
Purchase #3	$47.92	13.184%	$54.2378	$54.24	$54.25	$54.20
Purchase #4	$79.89	12.810%	$90.1239	$90.12	$90.10	$90.10
Purchase #5	$46.41	11.288%	$51.6488	$51.65	$51.65	$51.60
Purchase #6	$208.44	10.604%	$230.543	$230.54	$230.55	$230.50
Purchase #7	$204.59	4.344%	$213.4774	$213.48	$213.50	$213.50
7 purchase totals =	$947.85		$1,026.8564	$1,026.85	$1,026.90	$1,026.70