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	$119.97	9.133%	$130.9269	$130.93	$130.95	$130.90
Purchase #2	$191.71	11.212%	$213.2045	$213.20	$213.20	$213.20
Purchase #3	$215.30	13.407%	$244.1653	$244.17	$244.15	$244.20
Purchase #4	$79.91	13.173%	$90.4365	$90.44	$90.45	$90.40
Purchase #5	$155.33	13.217%	$175.86	$175.86	$175.85	$175.90
Purchase #6	$81.62	13.558%	$92.686	$92.69	$92.70	$92.70
Purchase #7	$87.50	13.845%	$99.6144	$99.61	$99.60	$99.60
7 purchase totals =	$931.34		$1,046.8936	$1,046.90	$1,046.90	$1,046.90