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	$197.80	12.488%	$222.5013	$222.50	$222.50	$222.50
Purchase #2	$181.53	8.823%	$197.5464	$197.55	$197.55	$197.50
Purchase #3	$69.27	13.411%	$78.5598	$78.56	$78.55	$78.60
Purchase #4	$59.38	11.306%	$66.0935	$66.09	$66.10	$66.10
Purchase #5	$229.76	3.120%	$236.9285	$236.93	$236.95	$236.90
Purchase #6	$85.61	11.328%	$95.3079	$95.31	$95.30	$95.30
Purchase #7	$250.78	5.812%	$265.3553	$265.36	$265.35	$265.40
7 purchase totals =	$1,074.13		$1,162.2927	$1,162.30	$1,162.30	$1,162.30