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	$63.33	13.258%	$71.7263	$71.73	$71.75	$71.70
Purchase #2	$150.89	9.545%	$165.2925	$165.29	$165.30	$165.30
Purchase #3	$167.56	6.294%	$178.1062	$178.11	$178.10	$178.10
Purchase #4	$249.82	7.714%	$269.0911	$269.09	$269.10	$269.10
Purchase #5	$22.37	6.625%	$23.852	$23.85	$23.85	$23.90
Purchase #6	$224.37	7.777%	$241.8193	$241.82	$241.80	$241.80
Purchase #7	$215.71	10.761%	$238.9226	$238.92	$238.90	$238.90
7 purchase totals =	$1,094.05		$1,188.8100	$1,188.81	$1,188.80	$1,188.80