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	$99.31	13.723%	$112.9383	$112.94	$112.95	$112.90
Purchase #2	$124.41	6.373%	$132.3386	$132.34	$132.35	$132.30
Purchase #3	$167.86	4.648%	$175.6621	$175.66	$175.65	$175.70
Purchase #4	$192.89	4.419%	$201.4138	$201.41	$201.40	$201.40
Purchase #5	$242.72	5.522%	$256.123	$256.12	$256.10	$256.10
Purchase #6	$43.28	4.523%	$45.2376	$45.24	$45.25	$45.20
Purchase #7	$213.93	7.121%	$229.164	$229.16	$229.15	$229.20
7 purchase totals =	$1,084.40		$1,152.8774	$1,152.87	$1,152.85	$1,152.80