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	$234.50	4.867%	$245.9131	$245.91	$245.90	$245.90
Purchase #2	$53.59	9.607%	$58.7384	$58.74	$58.75	$58.70
Purchase #3	$202.45	3.615%	$209.7686	$209.77	$209.75	$209.80
Purchase #4	$205.30	4.391%	$214.3147	$214.31	$214.30	$214.30
Purchase #5	$35.64	13.668%	$40.5113	$40.51	$40.50	$40.50
Purchase #6	$148.72	13.373%	$168.6083	$168.61	$168.60	$168.60
Purchase #7	$90.39	7.732%	$97.379	$97.38	$97.40	$97.40
7 purchase totals =	$970.59		$1,035.2334	$1,035.23	$1,035.20	$1,035.20