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	$188.72	13.595%	$214.3765	$214.38	$214.40	$214.40
Purchase #2	$168.46	13.287%	$190.8433	$190.84	$190.85	$190.80
Purchase #3	$96.85	13.370%	$109.7988	$109.80	$109.80	$109.80
Purchase #4	$54.68	12.294%	$61.4024	$61.40	$61.40	$61.40
Purchase #5	$148.52	12.849%	$167.6033	$167.60	$167.60	$167.60
Purchase #6	$201.95	4.564%	$211.167	$211.17	$211.15	$211.20
Purchase #7	$51.56	7.612%	$55.4847	$55.48	$55.50	$55.50
7 purchase totals =	$910.74		$1,010.6760	$1,010.67	$1,010.70	$1,010.70