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	$153.27	13.722%	$174.3017	$174.30	$174.30	$174.30
Purchase #2	$244.85	5.520%	$258.3657	$258.37	$258.35	$258.40
Purchase #3	$96.53	13.477%	$109.5393	$109.54	$109.55	$109.50
Purchase #4	$106.96	6.862%	$114.2996	$114.30	$114.30	$114.30
Purchase #5	$179.37	13.472%	$203.5347	$203.53	$203.55	$203.50
Purchase #6	$56.40	5.356%	$59.4208	$59.42	$59.40	$59.40
Purchase #7	$102.54	4.723%	$107.383	$107.38	$107.40	$107.40
7 purchase totals =	$939.92		$1,026.8448	$1,026.84	$1,026.85	$1,026.80