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	$79.29	8.455%	$85.994	$85.99	$86.00	$86.00
Purchase #2	$248.63	8.549%	$269.8854	$269.89	$269.90	$269.90
Purchase #3	$80.77	6.636%	$86.1299	$86.13	$86.15	$86.10
Purchase #4	$152.69	12.347%	$171.5426	$171.54	$171.55	$171.50
Purchase #5	$107.27	4.711%	$112.3235	$112.32	$112.30	$112.30
Purchase #6	$160.56	13.244%	$181.8246	$181.82	$181.80	$181.80
Purchase #7	$185.61	5.834%	$196.4385	$196.44	$196.45	$196.40
7 purchase totals =	$1,014.82		$1,104.1385	$1,104.13	$1,104.15	$1,104.00