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	$84.49	13.347%	$95.7669	$95.77	$95.75	$95.80
Purchase #2	$172.73	7.807%	$186.215	$186.22	$186.20	$186.20
Purchase #3	$132.45	6.631%	$141.2328	$141.23	$141.25	$141.20
Purchase #4	$132.45	5.304%	$139.4751	$139.48	$139.50	$139.50
Purchase #5	$138.66	12.609%	$156.1436	$156.14	$156.15	$156.10
Purchase #6	$126.52	7.134%	$135.5459	$135.55	$135.55	$135.50
Purchase #7	$215.41	11.839%	$240.9124	$240.91	$240.90	$240.90
7 purchase totals =	$1,002.71		$1,095.2917	$1,095.30	$1,095.30	$1,095.20