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	$219.64	13.119%	$248.4546	$248.45	$248.45	$248.50
Purchase #2	$19.48	5.181%	$20.4893	$20.49	$20.50	$20.50
Purchase #3	$113.50	6.673%	$121.0739	$121.07	$121.05	$121.10
Purchase #4	$89.33	10.386%	$98.6078	$98.61	$98.60	$98.60
Purchase #5	$195.98	7.133%	$209.9593	$209.96	$209.95	$210.00
Purchase #6	$106.59	4.341%	$111.2171	$111.22	$111.20	$111.20
Purchase #7	$218.56	8.712%	$237.6009	$237.60	$237.60	$237.60
7 purchase totals =	$963.08		$1,047.4029	$1,047.40	$1,047.35	$1,047.50