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	$216.81	4.751%	$227.1106	$227.11	$227.10	$227.10
Purchase #2	$92.34	10.437%	$101.9775	$101.98	$102.00	$102.00
Purchase #3	$161.63	6.594%	$172.2879	$172.29	$172.30	$172.30
Purchase #4	$215.56	6.459%	$229.483	$229.48	$229.50	$229.50
Purchase #5	$166.91	13.138%	$188.8386	$188.84	$188.85	$188.80
Purchase #6	$128.80	9.748%	$141.3554	$141.36	$141.35	$141.40
Purchase #7	$46.85	13.850%	$53.3387	$53.34	$53.35	$53.30
7 purchase totals =	$1,028.90		$1,114.3917	$1,114.40	$1,114.45	$1,114.40