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	$57.63	7.831%	$62.143	$62.14	$62.15	$62.10
Purchase #2	$187.88	4.701%	$196.7122	$196.71	$196.70	$196.70
Purchase #3	$82.43	3.473%	$85.2928	$85.29	$85.30	$85.30
Purchase #4	$80.50	6.866%	$86.0271	$86.03	$86.05	$86.00
Purchase #5	$38.98	12.157%	$43.7188	$43.72	$43.70	$43.70
Purchase #6	$146.27	13.216%	$165.601	$165.60	$165.60	$165.60
Purchase #7	$97.85	6.785%	$104.4891	$104.49	$104.50	$104.50
7 purchase totals =	$691.54		$743.9840	$743.98	$744.00	$743.90