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	$141.34	7.758%	$152.3052	$152.31	$152.30	$152.30
Purchase #2	$238.73	6.842%	$255.0639	$255.06	$255.05	$255.10
Purchase #3	$67.80	5.726%	$71.6822	$71.68	$71.70	$71.70
Purchase #4	$60.63	10.120%	$66.7658	$66.77	$66.75	$66.80
Purchase #5	$80.78	11.338%	$89.9388	$89.94	$89.95	$89.90
Purchase #6	$119.72	11.637%	$133.6518	$133.65	$133.65	$133.70
Purchase #7	$168.49	10.586%	$186.3264	$186.33	$186.35	$186.30
7 purchase totals =	$877.49		$955.7341	$955.74	$955.75	$955.80