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	$184.28	11.113%	$204.759	$204.76	$204.75	$204.80
Purchase #2	$139.34	13.802%	$158.5717	$158.57	$158.55	$158.60
Purchase #3	$230.95	5.428%	$243.486	$243.49	$243.50	$243.50
Purchase #4	$129.57	5.315%	$136.4566	$136.46	$136.45	$136.50
Purchase #5	$178.37	3.703%	$184.975	$184.98	$185.00	$185.00
Purchase #6	$25.59	8.601%	$27.791	$27.79	$27.80	$27.80
Purchase #7	$194.69	10.671%	$215.4654	$215.47	$215.45	$215.50
7 purchase totals =	$1,082.79		$1,171.5047	$1,171.52	$1,171.50	$1,171.70