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	$105.50	11.770%	$117.9174	$117.92	$117.90	$117.90
Purchase #2	$142.32	3.576%	$147.4094	$147.41	$147.40	$147.40
Purchase #3	$68.92	5.727%	$72.867	$72.87	$72.85	$72.90
Purchase #4	$49.83	3.445%	$51.5466	$51.55	$51.55	$51.50
Purchase #5	$171.38	13.425%	$194.3878	$194.39	$194.40	$194.40
Purchase #6	$234.60	6.709%	$250.3393	$250.34	$250.35	$250.30
Purchase #7	$180.27	13.401%	$204.428	$204.43	$204.45	$204.40
7 purchase totals =	$952.82		$1,038.8955	$1,038.91	$1,038.90	$1,038.80