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	$227.33	7.654%	$244.7298	$244.73	$244.75	$244.70
Purchase #2	$134.31	13.140%	$151.9583	$151.96	$151.95	$152.00
Purchase #3	$169.54	12.559%	$190.8325	$190.83	$190.85	$190.80
Purchase #4	$59.43	7.230%	$63.7268	$63.73	$63.75	$63.70
Purchase #5	$192.69	12.230%	$216.256	$216.26	$216.25	$216.30
Purchase #6	$157.55	7.372%	$169.1646	$169.16	$169.15	$169.20
Purchase #7	$51.52	3.303%	$53.2217	$53.22	$53.20	$53.20
7 purchase totals =	$992.37		$1,089.8897	$1,089.89	$1,089.90	$1,089.90