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	$221.69	13.566%	$251.7645	$251.76	$251.75	$251.80
Purchase #2	$83.54	3.503%	$86.4664	$86.47	$86.45	$86.50
Purchase #3	$106.69	4.326%	$111.3054	$111.31	$111.30	$111.30
Purchase #4	$114.67	4.593%	$119.9368	$119.94	$119.95	$119.90
Purchase #5	$167.94	4.499%	$175.4956	$175.50	$175.50	$175.50
Purchase #6	$201.62	7.402%	$216.5439	$216.54	$216.55	$216.50
Purchase #7	$122.49	8.351%	$132.7191	$132.72	$132.70	$132.70
7 purchase totals =	$1,018.64		$1,094.2317	$1,094.24	$1,094.20	$1,094.20