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	$214.59	4.107%	$223.4032	$223.40	$223.40	$223.40
Purchase #2	$85.76	6.733%	$91.5342	$91.53	$91.55	$91.50
Purchase #3	$198.27	8.806%	$215.7297	$215.73	$215.75	$215.70
Purchase #4	$109.55	3.726%	$113.6318	$113.63	$113.65	$113.60
Purchase #5	$181.30	8.196%	$196.1593	$196.16	$196.15	$196.20
Purchase #6	$11.32	3.608%	$11.7284	$11.73	$11.75	$11.70
Purchase #7	$231.26	8.219%	$250.2673	$250.27	$250.25	$250.30
7 purchase totals =	$1,032.05		$1,102.4539	$1,102.45	$1,102.50	$1,102.40