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	$195.58	9.136%	$213.4482	$213.45	$213.45	$213.40
Purchase #2	$152.53	9.563%	$167.1164	$167.12	$167.10	$167.10
Purchase #3	$137.45	8.211%	$148.736	$148.74	$148.75	$148.70
Purchase #4	$184.59	6.363%	$196.3355	$196.34	$196.35	$196.30
Purchase #5	$247.48	11.216%	$275.2374	$275.24	$275.25	$275.20
Purchase #6	$138.86	12.164%	$155.7509	$155.75	$155.75	$155.80
Purchase #7	$26.28	10.645%	$29.0775	$29.08	$29.10	$29.10
7 purchase totals =	$1,082.77		$1,185.7019	$1,185.72	$1,185.75	$1,185.60