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	$58.85	4.508%	$61.503	$61.50	$61.50	$61.50
Purchase #2	$34.61	7.705%	$37.2767	$37.28	$37.30	$37.30
Purchase #3	$55.46	3.774%	$57.5531	$57.55	$57.55	$57.60
Purchase #4	$5.36	3.696%	$5.5581	$5.56	$5.55	$5.60
Purchase #5	$40.85	9.328%	$44.6605	$44.66	$44.65	$44.70
Purchase #6	$86.74	3.336%	$89.6336	$89.63	$89.65	$89.60
Purchase #7	$67.51	5.685%	$71.3479	$71.35	$71.35	$71.30
7 purchase totals =	$349.38		$367.5329	$367.53	$367.55	$367.60