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	$203.66	7.767%	$219.4783	$219.48	$219.50	$219.50
Purchase #2	$68.93	6.300%	$73.2726	$73.27	$73.25	$73.30
Purchase #3	$200.84	13.195%	$227.3408	$227.34	$227.35	$227.30
Purchase #4	$203.47	4.809%	$213.2549	$213.25	$213.25	$213.30
Purchase #5	$38.86	10.554%	$42.9613	$42.96	$42.95	$43.00
Purchase #6	$162.94	9.434%	$178.3118	$178.31	$178.30	$178.30
Purchase #7	$132.81	11.733%	$148.3926	$148.39	$148.40	$148.40
7 purchase totals =	$1,011.51		$1,103.0123	$1,103.00	$1,103.00	$1,103.10