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	$83.62	13.605%	$94.9965	$95.00	$95.00	$95.00
Purchase #2	$188.77	11.458%	$210.3993	$210.40	$210.40	$210.40
Purchase #3	$29.50	7.827%	$31.809	$31.81	$31.80	$31.80
Purchase #4	$98.61	13.372%	$111.7961	$111.80	$111.80	$111.80
Purchase #5	$195.47	13.352%	$221.5692	$221.57	$221.55	$221.60
Purchase #6	$167.99	10.164%	$185.0645	$185.06	$185.05	$185.10
Purchase #7	$56.64	6.867%	$60.5295	$60.53	$60.55	$60.50
7 purchase totals =	$820.60		$916.1641	$916.17	$916.15	$916.20