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	$174.97	13.636%	$198.8289	$198.83	$198.85	$198.80
Purchase #2	$63.91	7.611%	$68.7742	$68.77	$68.75	$68.80
Purchase #3	$198.47	12.754%	$223.7829	$223.78	$223.80	$223.80
Purchase #4	$146.31	13.420%	$165.9448	$165.94	$165.95	$165.90
Purchase #5	$202.43	6.585%	$215.76	$215.76	$215.75	$215.80
Purchase #6	$46.72	12.334%	$52.4824	$52.48	$52.50	$52.50
Purchase #7	$173.88	6.627%	$185.403	$185.40	$185.40	$185.40
7 purchase totals =	$1,006.69		$1,110.9762	$1,110.96	$1,111.00	$1,111.00