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	$196.34	6.198%	$208.5092	$208.51	$208.50	$208.50
Purchase #2	$221.29	10.198%	$243.8572	$243.86	$243.85	$243.90
Purchase #3	$152.67	3.700%	$158.3188	$158.32	$158.30	$158.30
Purchase #4	$177.65	6.359%	$188.9468	$188.95	$188.95	$188.90
Purchase #5	$155.76	7.437%	$167.3439	$167.34	$167.35	$167.30
Purchase #6	$108.60	4.261%	$113.2274	$113.23	$113.25	$113.20
Purchase #7	$81.86	9.466%	$89.6089	$89.61	$89.60	$89.60
7 purchase totals =	$1,094.17		$1,169.8122	$1,169.82	$1,169.80	$1,169.70