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	$197.29	4.295%	$205.7636	$205.76	$205.75	$205.80
Purchase #2	$221.35	7.652%	$238.2877	$238.29	$238.30	$238.30
Purchase #3	$85.70	6.774%	$91.5053	$91.51	$91.50	$91.50
Purchase #4	$125.52	4.625%	$131.3253	$131.33	$131.35	$131.30
Purchase #5	$179.75	3.261%	$185.6116	$185.61	$185.60	$185.60
Purchase #6	$167.50	7.565%	$180.1714	$180.17	$180.15	$180.20
Purchase #7	$116.49	11.476%	$129.8584	$129.86	$129.85	$129.90
7 purchase totals =	$1,093.60		$1,162.5233	$1,162.53	$1,162.50	$1,162.60