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	$126.59	3.405%	$130.9004	$130.90	$130.90	$130.90
Purchase #2	$47.53	7.142%	$50.9246	$50.92	$50.90	$50.90
Purchase #3	$158.53	11.364%	$176.5453	$176.55	$176.55	$176.50
Purchase #4	$145.29	9.249%	$158.7279	$158.73	$158.75	$158.70
Purchase #5	$245.71	5.779%	$259.9096	$259.91	$259.90	$259.90
Purchase #6	$167.86	6.638%	$179.0025	$179.00	$179.00	$179.00
Purchase #7	$212.43	7.628%	$228.6342	$228.63	$228.65	$228.60
7 purchase totals =	$1,103.94		$1,184.6445	$1,184.64	$1,184.65	$1,184.50