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	$162.36	8.379%	$175.9641	$175.96	$175.95	$176.00
Purchase #2	$165.36	11.321%	$184.0804	$184.08	$184.10	$184.10
Purchase #3	$131.99	10.695%	$146.1063	$146.11	$146.10	$146.10
Purchase #4	$78.51	8.712%	$85.3498	$85.35	$85.35	$85.30
Purchase #5	$140.89	13.155%	$159.4241	$159.42	$159.40	$159.40
Purchase #6	$204.50	10.712%	$226.406	$226.41	$226.40	$226.40
Purchase #7	$167.86	10.301%	$185.1513	$185.15	$185.15	$185.20
7 purchase totals =	$1,051.47		$1,162.4820	$1,162.48	$1,162.45	$1,162.50