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	$85.97	12.640%	$96.8366	$96.84	$96.85	$96.80
Purchase #2	$231.89	9.614%	$254.1839	$254.18	$254.20	$254.20
Purchase #3	$188.25	4.193%	$196.1433	$196.14	$196.15	$196.10
Purchase #4	$38.89	6.326%	$41.3502	$41.35	$41.35	$41.40
Purchase #5	$145.36	9.761%	$159.5486	$159.55	$159.55	$159.50
Purchase #6	$137.53	11.310%	$153.0846	$153.08	$153.10	$153.10
Purchase #7	$119.83	11.519%	$133.6332	$133.63	$133.65	$133.60
7 purchase totals =	$947.72		$1,034.7804	$1,034.77	$1,034.85	$1,034.70