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	$193.46	9.795%	$212.4094	$212.41	$212.40	$212.40
Purchase #2	$168.82	13.117%	$190.9641	$190.96	$190.95	$191.00
Purchase #3	$124.38	10.465%	$137.3964	$137.40	$137.40	$137.40
Purchase #4	$139.26	4.385%	$145.3666	$145.37	$145.35	$145.40
Purchase #5	$5.29	3.526%	$5.4765	$5.48	$5.50	$5.50
Purchase #6	$175.52	5.633%	$185.407	$185.41	$185.40	$185.40
Purchase #7	$206.71	13.330%	$234.2644	$234.26	$234.25	$234.30
7 purchase totals =	$1,013.44		$1,111.2844	$1,111.29	$1,111.25	$1,111.40