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	$211.88	10.327%	$233.7608	$233.76	$233.75	$233.80
Purchase #2	$191.54	7.157%	$205.2485	$205.25	$205.25	$205.20
Purchase #3	$52.56	7.520%	$56.5125	$56.51	$56.50	$56.50
Purchase #4	$188.64	4.800%	$197.6947	$197.69	$197.70	$197.70
Purchase #5	$100.84	10.801%	$111.7317	$111.73	$111.75	$111.70
Purchase #6	$238.96	12.530%	$268.9017	$268.90	$268.90	$268.90
Purchase #7	$35.55	5.111%	$37.367	$37.37	$37.35	$37.40
7 purchase totals =	$1,019.97		$1,111.2169	$1,111.21	$1,111.20	$1,111.20