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	$148.98	8.161%	$161.1383	$161.14	$161.15	$161.10
Purchase #2	$52.97	11.597%	$59.1129	$59.11	$59.10	$59.10
Purchase #3	$82.83	8.410%	$89.796	$89.80	$89.80	$89.80
Purchase #4	$144.30	4.141%	$150.2755	$150.28	$150.30	$150.30
Purchase #5	$200.43	3.218%	$206.8798	$206.88	$206.90	$206.90
Purchase #6	$224.37	10.488%	$247.9019	$247.90	$247.90	$247.90
Purchase #7	$236.52	4.428%	$246.9931	$246.99	$247.00	$247.00
7 purchase totals =	$1,090.40		$1,162.0975	$1,162.10	$1,162.15	$1,162.10