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	$52.65	10.577%	$58.2188	$58.22	$58.20	$58.20
Purchase #2	$85.97	4.433%	$89.7811	$89.78	$89.80	$89.80
Purchase #3	$161.95	7.703%	$174.425	$174.43	$174.45	$174.40
Purchase #4	$87.66	13.869%	$99.8176	$99.82	$99.80	$99.80
Purchase #5	$203.46	4.434%	$212.4814	$212.48	$212.50	$212.50
Purchase #6	$180.71	4.487%	$188.8185	$188.82	$188.80	$188.80
Purchase #7	$189.58	4.680%	$198.4523	$198.45	$198.45	$198.50
7 purchase totals =	$961.98		$1,021.9947	$1,022.00	$1,022.00	$1,022.00