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	$32.30	5.140%	$33.9602	$33.96	$33.95	$34.00
Purchase #2	$124.38	7.297%	$133.456	$133.46	$133.45	$133.50
Purchase #3	$172.61	5.722%	$182.4867	$182.49	$182.50	$182.50
Purchase #4	$176.27	11.539%	$196.6098	$196.61	$196.60	$196.60
Purchase #5	$219.86	10.452%	$242.8398	$242.84	$242.85	$242.80
Purchase #6	$21.71	3.680%	$22.5089	$22.51	$22.50	$22.50
Purchase #7	$185.57	13.780%	$211.1415	$211.14	$211.15	$211.10
7 purchase totals =	$932.70		$1,023.0029	$1,023.01	$1,023.00	$1,023.00