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	$143.38	6.602%	$152.8459	$152.85	$152.85	$152.80
Purchase #2	$25.90	9.556%	$28.375	$28.38	$28.40	$28.40
Purchase #3	$12.84	11.846%	$14.361	$14.36	$14.35	$14.40
Purchase #4	$200.42	5.659%	$211.7618	$211.76	$211.75	$211.80
Purchase #5	$122.35	4.199%	$127.4875	$127.49	$127.50	$127.50
Purchase #6	$98.39	12.861%	$111.0439	$111.04	$111.05	$111.00
Purchase #7	$213.65	7.223%	$229.0819	$229.08	$229.10	$229.10
7 purchase totals =	$816.93		$874.9570	$874.96	$875.00	$875.00