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	$211.84	5.121%	$222.6883	$222.69	$222.70	$222.70
Purchase #2	$29.84	10.190%	$32.8807	$32.88	$32.90	$32.90
Purchase #3	$155.87	6.727%	$166.3554	$166.36	$166.35	$166.40
Purchase #4	$160.96	13.458%	$182.622	$182.62	$182.60	$182.60
Purchase #5	$170.45	13.702%	$193.8051	$193.81	$193.80	$193.80
Purchase #6	$216.74	11.870%	$242.467	$242.47	$242.45	$242.50
Purchase #7	$41.77	8.194%	$45.1926	$45.19	$45.20	$45.20
7 purchase totals =	$987.47		$1,086.0111	$1,086.02	$1,086.00	$1,086.10