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	$196.77	3.843%	$204.3319	$204.33	$204.35	$204.30
Purchase #2	$200.57	8.439%	$217.4961	$217.50	$217.50	$217.50
Purchase #3	$111.63	9.710%	$122.4693	$122.47	$122.45	$122.50
Purchase #4	$80.93	12.840%	$91.3214	$91.32	$91.30	$91.30
Purchase #5	$200.38	9.355%	$219.1255	$219.13	$219.15	$219.10
Purchase #6	$204.89	3.181%	$211.4076	$211.41	$211.40	$211.40
Purchase #7	$82.31	3.433%	$85.1357	$85.14	$85.15	$85.10
7 purchase totals =	$1,077.48		$1,151.2875	$1,151.30	$1,151.30	$1,151.20