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	$228.71	9.480%	$250.3917	$250.39	$250.40	$250.40
Purchase #2	$46.60	3.574%	$48.2655	$48.27	$48.25	$48.30
Purchase #3	$100.64	3.626%	$104.2892	$104.29	$104.30	$104.30
Purchase #4	$162.78	7.841%	$175.5436	$175.54	$175.55	$175.50
Purchase #5	$206.74	12.794%	$233.1903	$233.19	$233.20	$233.20
Purchase #6	$31.68	13.390%	$35.922	$35.92	$35.90	$35.90
Purchase #7	$233.71	13.217%	$264.5995	$264.60	$264.60	$264.60
7 purchase totals =	$1,010.86		$1,112.2018	$1,112.20	$1,112.20	$1,112.20