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	$218.85	11.502%	$244.0221	$244.02	$244.00	$244.00
Purchase #2	$241.88	4.612%	$253.0355	$253.04	$253.05	$253.00
Purchase #3	$125.73	10.687%	$139.1668	$139.17	$139.15	$139.20
Purchase #4	$177.43	10.617%	$196.2677	$196.27	$196.25	$196.30
Purchase #5	$141.71	12.748%	$159.7752	$159.78	$159.80	$159.80
Purchase #6	$18.57	9.840%	$20.3973	$20.40	$20.40	$20.40
Purchase #7	$33.59	8.774%	$36.5372	$36.54	$36.55	$36.50
7 purchase totals =	$957.76		$1,049.2018	$1,049.22	$1,049.20	$1,049.20