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	$201.56	6.445%	$214.5505	$214.55	$214.55	$214.60
Purchase #2	$89.93	12.314%	$101.004	$101.00	$101.00	$101.00
Purchase #3	$75.72	3.225%	$78.162	$78.16	$78.15	$78.20
Purchase #4	$237.78	3.403%	$245.8717	$245.87	$245.85	$245.90
Purchase #5	$178.88	9.734%	$196.2922	$196.29	$196.30	$196.30
Purchase #6	$219.59	9.442%	$240.3237	$240.32	$240.30	$240.30
Purchase #7	$193.54	13.304%	$219.2886	$219.29	$219.30	$219.30
7 purchase totals =	$1,197.00		$1,295.4927	$1,295.48	$1,295.45	$1,295.60