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	$197.63	10.451%	$218.2843	$218.28	$218.30	$218.30
Purchase #2	$153.71	8.318%	$166.4956	$166.50	$166.50	$166.50
Purchase #3	$67.46	6.358%	$71.7491	$71.75	$71.75	$71.70
Purchase #4	$179.89	4.864%	$188.6398	$188.64	$188.65	$188.60
Purchase #5	$197.25	7.873%	$212.7795	$212.78	$212.80	$212.80
Purchase #6	$208.57	7.186%	$223.5578	$223.56	$223.55	$223.60
Purchase #7	$174.83	3.139%	$180.3179	$180.32	$180.30	$180.30
7 purchase totals =	$1,179.34		$1,261.8240	$1,261.83	$1,261.85	$1,261.80