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	$205.74	10.347%	$227.0279	$227.03	$227.05	$227.00
Purchase #2	$55.91	5.701%	$59.0974	$59.10	$59.10	$59.10
Purchase #3	$71.68	9.440%	$78.4466	$78.45	$78.45	$78.40
Purchase #4	$227.80	4.143%	$237.2378	$237.24	$237.25	$237.20
Purchase #5	$217.52	9.422%	$238.0147	$238.01	$238.00	$238.00
Purchase #6	$204.57	9.115%	$223.2166	$223.22	$223.20	$223.20
Purchase #7	$82.80	10.488%	$91.4841	$91.48	$91.50	$91.50
7 purchase totals =	$1,066.02		$1,154.5251	$1,154.53	$1,154.55	$1,154.40