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	$209.55	4.519%	$219.0196	$219.02	$219.00	$219.00
Purchase #2	$167.48	4.336%	$174.7419	$174.74	$174.75	$174.70
Purchase #3	$86.99	3.266%	$89.8311	$89.83	$89.85	$89.80
Purchase #4	$161.39	11.351%	$179.7094	$179.71	$179.70	$179.70
Purchase #5	$34.57	9.136%	$37.7283	$37.73	$37.75	$37.70
Purchase #6	$103.78	5.569%	$109.5595	$109.56	$109.55	$109.60
Purchase #7	$241.44	6.562%	$257.2833	$257.28	$257.30	$257.30
7 purchase totals =	$1,005.20		$1,067.8731	$1,067.87	$1,067.90	$1,067.80