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	$218.57	12.241%	$245.3252	$245.33	$245.35	$245.30
Purchase #2	$209.57	5.205%	$220.4781	$220.48	$220.50	$220.50
Purchase #3	$103.34	7.525%	$111.1163	$111.12	$111.10	$111.10
Purchase #4	$121.36	7.824%	$130.8552	$130.86	$130.85	$130.90
Purchase #5	$229.49	6.256%	$243.8469	$243.85	$243.85	$243.80
Purchase #6	$172.78	4.814%	$181.0976	$181.10	$181.10	$181.10
Purchase #7	$113.76	8.856%	$123.8346	$123.83	$123.85	$123.80
7 purchase totals =	$1,168.87		$1,256.5539	$1,256.57	$1,256.60	$1,256.50